Treatment method for treating lower limbs using multi-member catheter assembly

ABSTRACT

In the treatment method, a surgeon introduces a catheter assembly into a blood vessel in an arm, and delivers a distal portion of the catheter assembly to a predetermined position of a lower limb through the blood vessel in the body. Moreover, in the treatment method, the surgeon pulls an inner catheter out of an outer catheter, causes a treatment device to advance to the treatment target through the inside of the outer catheter, and treats the treatment target by the treatment device.

CROSS REFERENCES TO RELATED APPLICATIONS

This application claims priority to Japanese Application No. 2013-114106filed on May 30, 2013 and Japanese Application No. 2014-067600 filed onMar. 28, 2014, the entire content of both of which is incorporatedherein by reference.

TECHNICAL FIELD

The present invention generally relates to a treatment method fortreating lower limbs using an intervention procedure. The presentinvention also generally relates to a catheter assembly including afirst catheter (outer catheter) and a second catheter (inner catheter)that is introduced into the lumen of the first catheter (outercatheter).

BACKGROUND DISCUSSION

Conventionally, during an intervention procedure, in many cases, acatheter is introduced into the femoral artery from the femoral regionof a patient, and the distal portion of the catheter is delivered to atreatment target in the lumen to treat the target. In recent years, aprocedure of providing treatment by introducing the catheter from theartery of arm, particularly, from the radial artery (or the brachialartery) (TRI: Trans Radial Intervention) has been conducted morefrequently, for the reasons that a patient suffers from only a slightphysical strain by the procedure and can leave the hospital soon.

For example, “Catheterization and Cardiovascular Interventions, Volume78, Issue 6, pp 823-839, 15 Nov. 2011 “Transradial arterial access forcoronary and peripheral procedures: Executive summary by the transradialcommittee of the SCAI” discloses a treatment method in whichPercutaneous Coronary Intervention (PCI) is conducted by introducing acatheter from an arm. The above document also discloses, as anapplication example of catheterization, a method of treating a lesionformed inside the blood vessel of a lower limb, for example, PeripheralArterial Disease (PAD) by delivering a catheter to the lesion.

SUMMARY

When an intervention procedure, in which a catheter is introduced fromthe artery of an arm (radial artery or brachial artery), is conducted totreat the lower limb, a catheter which has a sufficient length needs tobe used. However, if a catheter which has been simply lengthened interms of the full length is used, properties of the catheter (kinkresistance, torque-transmitting properties, operability, and the like)deteriorate when the catheter is delivered, and accordingly, a highdegree of skill is required for treating the lower limb.

The disclosure here relates to an intervention procedure in which acatheter is introduced from the arm to treat the lower limb. A treatmentmethod is disclosed which provides excellent treatment by making itrather easy to deliver a catheter to a treatment target inside the lumenof the lower limb. Also disclosed is a catheter assembly including afirst catheter and a second catheter that are suitable for anintervention procedure in which a catheter is introduced from the arm totreat the lower limb. The catheter assembly makes it possible torelatively easily withdraw a second catheter (inner catheter) from ablood vessel, while leaving a first catheter (outer catheter) and aguide wire inside the blood vessel, when a guide wire is inserted intothe catheter assembly.

One aspect of the disclosure here involves a treatment method fortreating a treatment target of at least one of the lower limbs. Thetreatment method includes introducing a catheter assembly, composed of afirst catheter and a second catheter disposed in the lumen of the firstcatheter, into a blood vessel of an arm, delivering a portion of thecatheter assembly by operating a portion exposed to the outside, anddelivering the distal end of the catheter assembly to a predeterminedposition of the lower limb through the aorta, advancing a treatmentdevice for treating the treatment target toward the treatment targetthrough the inside of the first catheter after the delivery step, andtreating the treatment target by the treatment device.

According to the above method, by using the catheter assembly composedof two catheters including the first and second catheters, a surgeon canrather smoothly deliver the catheter assembly to a predeterminedposition of the lower limb in the delivery step. That is, since thecatheter assembly has a double catheter structure composed of the firstand second catheters, the properties (kink resistance,torque-transmitting properties, operability, and the like) required atthe time of delivery are improved. As a result, even if the catheterassembly is long enough to reach the lower limb from the arm, thesurgeon can rather easily deliver the distal portion of the catheterassembly. Consequently, with this treatment method, the first cathetercan be efficiently disposed in a predetermined position, and thetreatment device can be rapidly and accurately delivered to thetreatment target through the inside of the first catheter, henceexcellent treatment can be provided.

In this case, the treatment method may further include, before advancingthe device, a catheter advance step in which the distal end of thesecond catheter or the distal end of a third catheter, which isintroduced after the second catheter is withdrawn, is caused to advancenear the treatment target through the inside of the first catheter. Inthe device advance step, the treatment device may be caused to advancethrough the lumen of the second catheter or the third catheter.

As described above, in the treatment method, since the second catheteror the third catheter is caused to advance from the first catheter, thetreatment device can be delivered to various blood vessels present inthe lower limb. That is, since the second catheter or the third catheterhaving a diameter smaller than that of the first catheter is deliveredto the blood vessels, even when the treatment target is present in asmaller blood vessel, the second catheter or the third catheter can becaused to advance near the treatment target, and then the treatmentdevice can be introduced.

When the treatment target is present in both the first and second lowerlimbs constituting the left and right lower limbs of a patient, thetreatment target of the first lower limb is treated in the treatmentstep. In this case, it is preferable for the treatment method to have,after the treatment step, a retreat step in which the distal end of thefirst catheter is caused to return to a connection position of a bloodvessel of the first lower limb and a blood vessel of the second lowerlimb, a step of delivery to an individual site in which the firstcatheter is delivered to a predetermined position of the second lowerlimb from the connection position after the retreat step, a step ofcausing a device to advance to an individual site in which an individualsite treatment device, which is for treating the treatment target of thesecond lower limb, is caused to advance to the treatment target of thesecond lower limb through the inside of the first catheter after thestep of delivery to an individual site, and an individual site treatmentstep in which the treatment target of the second lower limb is treatedby the individual site treatment device.

According to the above method, a surgeon can consecutively conduct anintervention procedure for the treatment target of each of the two lowerlimbs (the first and second lower limbs). That is, after treating thetreatment target of the first lower limb, the surgeon moves the firstcatheter to retreat to the connection position, and then providestreatment by moving the first catheter to advance to the treatmenttarget of the second lower limb. As a result, plural treatment targetspresent in different sites can be efficiently treated by a singletreatment.

In this case, the treatment method may further include, before theindividual site treatment, causing a catheter to advance to anindividual site in which the distal end of the second catheter or thedistal end of the third catheter, which is introduced after the secondcatheter is withdrawn, is caused to advance near the treatment target ofthe second lower limb through the inside of the first catheter. In thestep of causing a device to advance to an individual site, theindividual site treatment device may be caused to advance through thelumen of the second catheter or the third catheter.

As described above, even when the treatment target is present in twolower limbs, it is possible to guide the treatment device near thetreatment target by using a third catheter.

Moreover, in the introduction step, a sheath having an outer diameter ofequal to or smaller than 2.8 mm may be introduced into a blood vessel ofthe arm first, and then the catheter assembly may be introduced throughthe lumen of the sheath.

If the sheath having an outer diameter of 2.8 mm is used as above, acatheter that is quite thick (for example, having an outer diameter ofaround 2.4 mm) can be used as the first catheter. In the case, forexample, a surgeon can use the first catheter having a larger outerdiameter. If such a catheter is used, the catheter assembly becomesthick, hence the properties required at the time of delivery can befurther improved.

When the treatment target is present in a blood vessel closer to theperipheral side than to the popliteal artery in the lower limb, in thedelivery, the distal end of the catheter assembly may be positioned inthe femoral artery or the iliac artery, and in the advancement, thetreatment device may be sent to the femoral artery from the catheterassembly, and the treatment device may be caused to advance to thepopliteal artery. When the elongated catheter assembly is inserted intothe blood vessel, a puncture portion of the blood vessel can beprevented from being damaged by abrasion.

As described above, in the treatment method, the distal portion of thecatheter assembly is positioned in the femoral artery or the iliacartery during the delivery, and accordingly, the first catheter canassist advance of the treatment device in the device advance step.Moreover, since the outer diameter of the treatment device is smallerthan the inner diameter of the first catheter, the treatment device cansmoothly advance to the popliteal artery that is relatively meanderingmuch.

Alternatively, when the treatment target is present in a blood vesselcloser to the peripheral side than to the popliteal artery in the lowerlimb, in the delivery step, the distal end of the catheter assembly maybe positioned in the popliteal artery or in the blood vessel at theperipheral side.

As described above, the distal end of the catheter assembly ispositioned in the popliteal artery or in the blood vessel at theperipheral side, and accordingly, the target treatment which is formedin a portion near the knee, the knee, or the ankle can be excellentlytreated by the treatment device which will be delivered thereto later.

In this case, it is preferable for the treatment target to be present ina portion near the knee, the calf, or a portion near the ankle.

Even when the treatment target is present in a portion near the knee,the calf, or a portion near the ankle as above, the properties requiredat the time of delivering the catheter assembly having a doublestructure can be maintained. Accordingly, the treatment device can besmoothly delivered to the treatment target.

Moreover, the treatment device may be a delivery device by which anintraluminal prosthesis is delivered to and remains in the treatmenttarget, a balloon catheter that dilates the treatment target, or a drugapplying device that applies a drug to the treatment target. Examples ofthe intraluminal prosthesis include a stent. Examples of the drugapplying device include a drug eluting balloon catheter and a drugeluting stent.

If the delivery device, balloon catheter, or the drug applying device isused as above, a stenosed portion or an occluded portion formed in ablood vessel of the lower limb can be excellently treated.

When the catheter assembly is in an assembled state, it is preferablefor the first catheter and the second catheter to be fixed to each otherby a lock mechanism which is disposed in the proximal portion of each ofthe catheters.

If the first catheter and the second catheter are fixed by the lockmechanism as above, the first catheter and the second catheter can beintegrally operated when the catheter assembly is operated. Accordingly,the properties required at the time of delivering the catheter assemblyinserted into the blood vessel can be further improved.

Disclosed here is a treatment method for treating a treatment target ofat least one lower limb. The treatment method includes a supply stepthat supplies a catheter assembly in which an inner catheter is disposedin the lumen of an outer catheter, and the distal end of the innercatheter protrudes from the distal end of the outer catheter; a guidewire inserting step in which a guide wire is inserted into the catheterassembly; an introduction step in which the catheter assembly isintroduced into a blood vessel of an arm; a delivery step in which aportion of the catheter assembly that is exposed to the outside of thebody is operated, and the distal end of the catheter assembly isdelivered to a predetermined position of the lower limb through theaorta; an inner catheter withdrawal step in which the inner catheter iswithdrawn from the lumen of the outer catheter, in a state where theouter catheter and the guide wire are left inside the blood vessel afterthe delivery step; a device advance step in which a treatment device fortreating the treatment target is introduced into the blood vessel alongthe guide wire after the inner catheter withdrawal step, and caused toadvance to the treatment target through the inside of the outercatheter; and a treatment step in which the treatment target is treatedby the treatment device.

According to the above method, by using the catheter assembly composedof two catheters including the inner and outer catheters, a surgeon cansmoothly deliver the catheter assembly to a predetermined position ofthe lower limb along the guide wire in the delivery step. That is, thecatheter assembly has a double structure composed of an inner catheterand an outer catheter, and accordingly, properties (kink resistance,torque transmitting properties, operability, and the like) required atthe time of delivery are improved. Consequently, even if the catheterassembly is long enough to reach the lower limb from the arm, thesurgeon can easily deliver the distal portion of the catheter assembly.Moreover, when the guide wire is introduced into the catheter assembly,a gap between the inner surface of the outer catheter and the outersurface of the guide wire is reduced by the inner catheter. That is, thedistal end of the outer catheter inhibits a great step difference frombeing formed between the inner surface of the outer catheter and theouter surface of the guide wire. Therefore, a concern that the distalend of the catheter assembly may damage the blood vessel in the deliverystep can be allayed. As a result, in the treatment method, the outercatheter can be efficiently placed in a predetermined position, and thetreatment device can be rapidly and accurately delivered to thetreatment target through the inside of the outer catheter, henceexcellent treatment can be provided.

In this case, the outer catheter has a tubular outer catheter body, andan outer catheter hub that is disposed in the proximal end of the outercatheter body. The inner catheter has an inner catheter body that can beinserted into the outer catheter body, and an inner catheter hub that isdisposed in the proximal end of the inner catheter body and can beconnected to the outer catheter hub. In the supply step, the catheterassembly may be constituted by disposing the inner catheter body in anouter catheter lumen of the outer catheter body and connecting the innercatheter hub to the outer catheter hub.

As described above, if the inner catheter hub is connected to the outercatheter hub so as to fix the inner catheter to the outer catheter, theinner catheter and the outer catheter can be integrally operated whenthe catheter assembly is operated. Accordingly, the properties requiredat the time of delivering the catheter assembly inserted in to a bloodvessel can be further improved.

The inner catheter body has a shaft that extends to the distal end fromthe inner catheter hub and a tubular body that is disposed in the distalend of the shaft and includes an inner catheter lumen. In the supplystep, the catheter assembly may be constituted such that the distal endof the tubular body is disposed closer to the distal side than to thedistal end of the outer catheter body, and the proximal end of thetubular body is positioned in the outer catheter lumen of the outercatheter body.

In the catheter assembly constituted as above, the tubular body of theinner catheter is disposed in a predetermined area from a portion, whichis closer to the distal side than to the distal end of the outercatheter body, to the proximal end of the outer catheter body.Accordingly, in the guide wire insertion step, in an area from theproximal end of the tubular body to the distal end of the inner catheterhub, the guide wire is disposed to the outside of the lumen of the innercatheter. In other words, in a space between the proximal end of thetubular body and the distal end of the inner catheter hub, the guidewire is disposed in a space between the outer circumferential surface ofthe shaft and the inner circumferential surface of the outer catheter.That is, the inner catheter is a rapid exchange catheter. Accordingly,in the inner catheter withdrawal step, the guide wire makes a shortdistance move when passing through the lumen of the inner catheter. As aresult, it is possible to easily withdraw the inner catheter from theblood vessel while leaving the guide wire and the outer catheter in theblood vessel.

The tubular body has a second inner catheter lumen that opens in thedistal portion and the proximal portion. In the delivery step, a fluidmay be injected through the inner catheter hub of the catheter assembly,such that the fluid can be injected into the blood vessel through thesecond inner catheter lumen.

According to the above embodiment, when a surgeon wants to inject afluid such as contrast agent, physiological saline, or the like into theblood vessel in the delivery step, even if the guide wire is insertedinto the inner catheter lumen of the tubular body, the surgeon caninject the fluid into the blood vessel through the second inner catheterlumen of the tubular body. Accordingly, the surgeon can easily ascertainthe shape and the like of the blood vessel by administering, forexample, a contrast agent, and as a result, the catheter assembly can bemore rapidly delivered to the treatment target.

In the introduction step, a sheath having an outer diameter equal to orsmaller than 2.8 mm may be introduced into the blood vessel of the armfirst, and then the catheter assembly may be introduced through thelumen of the sheath.

If the sheath having an outer diameter of 2.8 mm is used as above, acatheter that is quite thick (for example, having an outer diameter ofaround 2.4 mm) can be used as the outer catheter. In the case, forexample, a surgeon can use the first catheter having a larger outerdiameter. If such a catheter is used, the catheter assembly becomesthick, hence the properties required at the time of delivery can befurther improved.

When the treatment target is present in a blood vessel closer to theperipheral side than to the popliteal artery in the lower limb, in thedelivery step, the distal end of the catheter assembly may be positionedin femoral artery or iliac artery, and in the device advance step, thetreatment device may be sent to the femoral artery from the catheterassembly, and the treatment device may be caused to advance to thepopliteal artery. When the long catheter assembly is inserted into theblood vessel, a puncture portion of the blood vessel can be preventedfrom being damaged by abrasion.

As described above, in the treatment method, the distal portion of thecatheter assembly is positioned in the femoral artery or the iliacartery in the delivery step, and accordingly, the outer catheter canassist advance of the treatment device in the device advance step.Moreover, since the outer diameter of the treatment device is smallerthan the inner diameter of the outer catheter, the treatment device cansmoothly advance to the popliteal artery that is relatively meanderingmuch.

Alternatively, when the treatment target is present in a blood vesselcloser to the peripheral side than to the popliteal artery in the lowerlimb, in the delivery step, the distal end of the catheter assembly maybe positioned in the popliteal artery or in the blood vessel at theperipheral side.

As described above, the distal end of the catheter assembly ispositioned in the popliteal artery or in the blood vessel at theperipheral side, and accordingly, the treatment target which is formedin a portion near the knee, the knee, or the ankle can be excellentlytreated by the treatment device which will be delivered thereto later.

In this case, it is preferable for the treatment target to present in aportion near the knee, the calf, or a portion near the ankle.

Even when the treatment target is present in a portion near the knee,the calf, or a portion near the ankle as above, the properties requiredat the time of delivering the catheter assembly having a doublestructure can be maintained. Accordingly, the treatment device can besmoothly delivered to the treatment target.

Moreover, the treatment device may be a delivery device by which anintraluminal prosthesis is delivered to and remains in the treatmenttarget, a balloon catheter that dilates the treatment target, or a drugapplying device that applies a drug to the treatment target. Examples ofthe intraluminal prosthesis include a stent. Examples of the drugapplying device include a drug eluting balloon catheter and a drugeluting stent.

If the delivery device, balloon catheter, or the drug applying device isused as above, a stenosed portion or an occluded portion formed in ablood vessel of the lower limb can be excellently treated.

The catheter assembly has an outer catheter that has a tubular outercatheter body and an outer catheter hub which is disposed in theproximal end of the outer catheter body; and an inner catheter that hasan inner catheter body which can be inserted into the outer catheterbody and an inner catheter hub which is disposed in the proximal end ofthe inner catheter body and has an inner catheter hub lumen formedinside the inner catheter and can be connected to the outer catheterhub. The inner catheter body has a shaft that extends to the distal endfrom the inner catheter hub, and a tubular body that is disposed in thedistal end of the shaft and has an inner catheter lumen which is formedin the inside thereof and opened to the outside in the distal portionand the proximal portion such that a guide wire can be inserted into thetubular body. When the outer catheter hub is connected to the innercatheter hub, the distal end of the tubular body of the inner catheterbody is disposed in a position closer to the distal side than to thedistal end of the outer catheter body; the proximal end of the tubularbody is disposed in a position closer to the proximal end than to thedistal end of the outer catheter body; and the proximal end of thetubular body is positioned in the outer catheter lumen of the outercatheter body.

In the catheter assembly constituted as above, when the outer catheterhub is connected to the inner catheter hub, the tubular body of theinner catheter is disposed in a predetermined area from a portion, whichis closer to the distal side than to the distal end of the outercatheter, to a portion, which is closer to the proximal side than to thedistal end of the outer catheter. Accordingly, when the outer catheterhub is connected to the inner catheter hub, and the guide wire is causedto protrude to the distal end of the inner catheter through the innercatheter hub lumen and the inner catheter lumen in this state, at thedistal end of the outer catheter, a step difference formed between theouter surface of the guide wire and the inner surface of the outercatheter becomes small due to the tubular body. Therefore, when beinginserted into the body lumen, the catheter assembly of the disclosedhere can reduce the strain that is imposed on the body by the distal endof the outer catheter.

Moreover, the catheter assembly is constituted such that the proximalend of the tubular body is positioned in the outer catheter lumen of theouter catheter body. The catheter assembly is also constituted such thatthe guide wire having been inserted into the inner catheter hub lumen isinserted into the proximal portion of the inner catheter lumen of thetubular body. That is, the guide wire is disposed between the outercircumferential surface of the shaft and the inner circumferentialsurface of the outer catheter body, and accordingly, in an area from theproximal side of the tubular body to the distal side of the innercatheter hub, the guide wire is positioned outside the lumen of theinner catheter. Therefore, when the guide wire is in the state of beinginserted in the catheter assembly, and the inner catheter is withdrawnin this state while leaving the guide wire and the outer catheterbehind, the guide wire having been inserted into the inner cathetermakes a short distance move when passing through the lumen of the innercatheter. Consequently, it is not necessary to use a long guide wire orlengthen the guide wire, and the guide wire can be easily withdrawn fromthe body lumen.

When the outer catheter hub is connected to the inner catheter hub, in across section of the distal end of the outer catheter body that isorthogonal to the axis of the outer catheter body, it is preferable forthe thickness of the tubular body in the radial direction thereof to begreater than the thickness of the outer catheter body in the radialdirection thereof. If the above constitution is adopted, the surgeon canreduce the step difference formed between the outer surface of the outercatheter body and the outer surface of the tubular body, while bringingthe distal end of the outer catheter into contact with the outer surfaceof the tubular body. Therefore, damage of body tissue can be suppressedas much as possible. Moreover, when the catheter assembly is insertedinto the body lumen, the impact exerted on the distal end of the outercatheter is mitigated due to the thickness of the inner catheter. As aresult, a surgeon can insert the outer catheter having a large innerdiameter and a small outer diameter (outer catheter that is thin in theradial direction thereof) to a lesion, without kinking the distal end ofthe outer catheter.

When the outer catheter hub is connected to the inner catheter hub, if alength between the distal end of the tubular body and the distal end ofthe outer catheter body in the axis direction is made smaller than alength between the distal end of the outer catheter body and theproximal end of the tubular body in the axis direction, the length ofthe tubular body accommodated inside the outer catheter becomessufficient, whereby the distal end area of the outer catheter can beprevented from being kinked. Accordingly, when inserting the catheterassembly into the body lumen, a surgeon can more safely inserting itinto the body lumen while sufficiently securing pushability orsufficiently transmitting torque to the distal side.

The outer catheter body has a rigidity transition portion in whichrigidity is reduced toward the distal end, and a rigidity uniformportion which is disposed in the proximal side of the rigiditytransition portion and in which the rigidity is uniform in the axisdirection. When the outer catheter hub is connected to the innercatheter hub, if the proximal end of the tubular body is positioned in aportion closer to the proximal side than to the distal end of therigidity uniform portion, the proximal end of the tubular body is notpositioned in the middle of the rigidity transition portion, andtransition of rigidity of the outer catheter body can be excellentlymaintained. Accordingly, when inserting the catheter assembly into thebody lumen, a surgeon can more safely insert the catheter assembly intothe body lumen while sufficiently securing pushability or sufficientlytransmitting torque to the distal side.

If the second inner catheter lumen, which is opened to the outside, isformed in the distal portion and the proximal portion of the tubularbody, a liquid such as a contrast agent or physiological saline can bedischarged from the distal end of the inner catheter, through the lumenof the outer catheter and the second inner catheter lumen. At this time,the liquid such as a contrast agent or physiological saline injectedfrom the inner catheter hub is supplied through the lumen of the outercatheter having a relatively large inner diameter, until the liquidreaches the second inner catheter lumen. Accordingly, pressure loss isreduced, and for example, even a contrast agent having a high viscositycan be easily pushed out by a weak force. Moreover, while the guide wireis being inserted into the catheter assembly, in the tubular body, asufficient clearance cannot be formed between the inner circumferentialsurface of the inner catheter lumen and the outer circumferentialsurface of the guide wire. Therefore, if the second inner catheter lumenis disposed in the tubular body in the catheter assembly, the liquidsuch as a contrast agent injected from the inner catheter hub can beexcellently discharged from the distal end of the tubular body.

If a shaft lumen which penetrates the shaft in the axis direction isformed in the shaft; if the second inner catheter lumen, which is incommunication with the shaft lumen and is opened to the outside in thedistal portion, is formed in the tubular body; and if a second innercatheter hub lumen, which is in communication with the shaft lumen andis opened to the outside, is formed in the inner catheter hub, a liquidsuch as a contrast agent or physiological saline can be discharged fromthe distal end of the inner catheter through the shaft lumen and thesecond catheter lumen. At this time, the liquid can be effectivelydelivered without coming into contact with the guide wire and beinginterrupted by the guide wire.

If the shaft is connected to the inner catheter hub in a positiondifferent from the position of the inner catheter hub lumen, a liquidcan be easily supplied into the lumen of the outer catheter through theinner catheter hub lumen, in a state where the outer catheter hub isbeing connected to the inner catheter hub.

If the inner catheter can be inserted into the tubular outer catheterbody of the outer catheter and has an inner catheter hub in which aninner catheter hub lumen opened to the outside in the distal portion andthe proximal portion is formed; a shaft which is connected to the innercatheter hub and extends to the distal end from the inner catheter hub;and a tubular body which is disposed in the distal end of the shaft andin which an inner catheter lumen opened to the outside in the distalportion and the proximal portion so as to enable a guide wire to beinserted into the lumen is formed, a liquid can be supplied into thelumen of the outer catheter through the inner catheter hub lumen, in astate where the inner catheter is being inserted into the outer catheterbody.

If the inner catheter hub can be connected to the outer catheter hubdisposed in the proximal end of the outer catheter body, a state wherethe inner catheter is being inserted into the outer catheter body can beexcellently maintained. Accordingly, operability is improved, and aliquid can be supplied into the lumen of the outer catheter through theinner catheter hub lumen.

When a lower limb is treated by an intervention procedure in which acatheter is introduced from an arm, the catheter can be easily deliveredto a treatment target, and excellent treatment can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of one embodiment of a treatmentmethod representing one example of the treatment method disclosed here.

FIG. 2 is a partial lateral cross-sectional exploded view of a catheterassembly and a sheath introducer used in the treatment method accordingto the first embodiment.

FIG. 3 is a first illustrative view showing the state of the catheterassembly introduced by the treatment method according to the firstembodiment.

FIG. 4A is a second illustrative view showing the way the distal portionof the catheter assembly operates by the treatment method according tothe first embodiment, and FIG. 4B is a third illustrative view showingthe way the distal portion of the catheter assembly operates by thetreatment method following FIG. 4A.

FIG. 5A is a fourth illustrative view of the treatment method followingFIG. 4B; FIG. 5B is a fifth illustrative view of the treatment methodfollowing FIG. 5A; FIG. 5C is a sixth illustrative view of the treatmentmethod following FIG. 5B; and FIG. 5D is a seventh illustrative view ofthe treatment method following FIG. 5C.

FIG. 6A is an eighth illustrative view of the treatment method followingFIG. 5D; FIG. 6B is a ninth illustrative view of the treatment methodfollowing FIG. 6A; and FIG. 6C is a tenth illustrative view of thetreatment method following FIG. 6B.

FIG. 7A is a schematic view showing a treatment device of a treatmentmethod according to a first modified example; FIG. 7B is a schematicview showing a treatment device of a treatment method according to asecond modified example; FIG. 7C is a schematic view showing a treatmentdevice of a treatment method according to a third modified example; andFIG. 7D is a schematic view showing a treatment device of a treatmentmethod according to a fourth modified example.

FIG. 8A is a first illustrative view showing a treatment methodaccording to a fifth modified example; FIG. 8B is a second illustrativeview of the treatment method following FIG. 8A; and FIG. 8C is a thirdillustrative view of the treatment method following FIG. 8B.

FIG. 9A is a first illustrative view showing a treatment methodaccording to a second embodiment representing another example of thetreatment method disclosed here, and FIG. 9B is a second illustrativeview of the treatment method following FIG. 9A.

FIG. 10A is a third illustrative view of the treatment method followingFIG. 9B, and FIG. 10B is a fourth illustrative view of the treatmentmethod following FIG. 10A.

FIG. 11A is a first illustrative view showing a treatment methodaccording to a sixth modified example; FIG. 11B is a second illustrativeview of the treatment method following FIG. 11A; and FIG. 11C is a thirdillustrative view of the treatment method following FIG. 11B.

FIG. 12 is a plan view showing a catheter assembly used in a treatmentmethod according to a third embodiment representing a further example ofthe treatment method disclosed here.

FIG. 13A is a plan view showing an outer catheter of the catheterassembly shown in FIG. 12, and FIG. 13B is a plan view showing an innercatheter of the catheter assembly shown in FIG. 12.

FIG. 14 is a vertical cross-sectional view of the proximal portion ofthe catheter assembly shown in FIG. 12.

FIG. 15 is a vertical cross-sectional view of the distal portion of thecatheter assembly shown in FIG. 12.

FIG. 16 is a first illustrative view showing a state where the catheterassembly used in the treatment method according to the third embodimentis introduced into a blood vessel.

FIG. 17 is a second illustrative view showing the way the distal portionof the catheter assembly used in the treatment method according to thethird embodiment operates. This is a schematic cross-sectional viewshowing the state where the catheter assembly is pushed into a bloodvessel.

FIG. 18 is a third illustrative view showing a state where the innercatheter is pulled out of the catheter assembly (an inner catheter andan outer catheter) used in the treatment method according to the thirdembodiment.

FIG. 19 is a fourth illustrative view showing the way the distal portionof the catheter assembly used in the treatment method according to thethird embodiment operates. This is a schematic cross-sectional viewshowing a state where the inner catheter is pulled out of the catheterassembly (an inner catheter and an outer catheter).

FIG. 20 is a fifth illustrative view showing a state where a ballooncatheter is introduced into a blood vessel through the outer catheter,after the inner catheter is pulled out of the catheter assembly used inthe treatment method according to the third embodiment.

FIG. 21 is a sixth illustrative view of the treatment method followingFIG. 20. This is a schematic cross-sectional view showing a state wherea balloon catheter is introduced into a blood vessel through the outercatheter, after the inner catheter is pulled out of the catheterassembly used in the treatment method according to the third embodiment.

FIG. 22 is a seventh illustrative view showing the way the distalportion of the catheter assembly used in the treatment method accordingto the third embodiment operates. This is a schematic cross-sectionalview showing a state where a balloon catheter having been inserted intoa blood vessel through the outer catheter is dilated, after the innercatheter is pulled out of the catheter assembly used in the treatmentmethod according to the third embodiment.

FIG. 23 shows a seventh modification example of the catheter assemblyused in the treatment method according to the third embodiment. This isa vertical cross-sectional view showing the distal portion of thecatheter assembly according to the seventh modification example.

FIG. 24 is a horizontal cross-sectional view taken along the sectionline XXIV-XXIV in FIG. 23.

FIG. 25 is a vertical cross-sectional view showing the proximal portionof the catheter assembly according to a seventh modified example.

FIG. 26 shows an eighth modified example of the catheter assembly usedin the treatment method according to the third embodiment. This is avertical cross-sectional view showing the distal portion of the catheterassembly according to the eighth modified example.

FIG. 27 is a horizontal cross-sectional view taken along the sectionline XXVII-XXVII of FIG. 26.

FIG. 28 is a vertical cross-sectional view showing the proximal portionof the catheter assembly according to the eighth modified example.

FIG. 29 is a plan view of a ninth modified example of the catheterassembly used in the treatment method according to the third embodiment.

DETAILED DESCRIPTION

Set forth below with reference to the drawing figures is a detaileddescription of embodiments of a treatment method representing examplesof the treatment method disclosed here.

A treatment method according to a first embodiment is an interventionprocedure that provides treatment inside a blood vessel 102 of a patient100 as shown in FIG. 1. This procedure provides treatment of a lesionformed in the blood vessel 102 of a lower limb 104. Examples of thetreatment target include a stenosed portion X that is formed whenthrombi and the like are accumulated in the popliteal artery. In thefollowing description, between a pair of lower limbs 104 (a left leg 104b: a first lower limb, a right leg 104 a: a second lower limb) of thepatient 100, the stenosed portion X formed in the left leg 104 b will betreated.

In the treatment method, an intervention device 10 is introduced fromthe blood vessel 102 of an arm 106 (upper limb), and the distal portionof the intervention device 10 is delivered to the stenosed portion X toprovide treatment. Therefore, the full length of the intervention device10 is sufficiently longer than that of a device used for, for example,percutaneous transluminal coronary angioplasty.

The intervention device 10 used for the treatment method includes acatheter assembly 12 that includes double catheters (an outer catheter14 and an inner catheter 16) and a treatment device 18 that treats thestenosed portion X. The catheter assembly 12 (hereinafter, simplyreferred to as “assembly 12”) is a so-called guiding catheter. Thecatheter assembly 12 is introduced into the blood vessel 102 of thepatient 100 first and then guides the treatment device 18 introducedafter the catheter assembly 12. The treatment device 18 has a treatmentportion 20 for providing treatment in the distal portion of thetreatment device 18. The treatment portion 20 advances to the stenosedportion X through the assembly 12.

In order to facilitate understanding of the treatment method accordingto the first embodiment, the process of the procedure will first beschematically described. In the treatment method, an introduction stepis first performed in which the assembly 12 is introduced into the bloodvessel 102 of the arm 106 of the patient 100. In the introduction step,for example, a sheath introducer 22 (see FIGS. 2 and 3) is inserted intoa right radial artery 200 present in a wrist 108 of a right arm 106 a,and the assembly 12 is introduced through the sheath introducer 22.

Next, a delivery step is performed in which the proximal side of theassembly 12 (portion of the assembly 12 exposed outside the body) isoperated to deliver a distal portion 12 a of the assembly 12 to apredetermined position of the lower limb 104 through the blood vessel102 in the body. When the distal portion 12 a of the assembly 12 isintroduced into the right radial artery 200 of the right arm 106 a, inthe delivery step, the distal portion 12 a is advanced along the rightradial artery 200, a right brachial artery 202, a right subclavianartery 204, and a brachiocephalic artery 206. Thereafter, the distalportion 12 a is delivered in order of an aortic arch 208, a thoracicaorta 210, an abdominal aorta 212, a left common iliac artery 214, aleft external iliac artery 216, and a left femoral artery 218.

After the delivery step, a pull-out step is performed in which the innercatheter 16 is pulled out of the outer catheter 14. That is, the innercatheter 16 is pulled out by being moved backward (proximal direction)while the outer catheter 14 is fixed or remains in position, and theouter catheter 14 is left inside the body of the patient 100.

After the inner catheter 16 is pulled out, a device advance step isperformed in which the treatment portion 20 of the treatment device 18is advanced through the inside of the outer catheter 14. A surgeoninserts the distal end of the treatment device 18 into the proximal endof the lumen in the outer catheter 14 and then advances the treatmentdevice 18 in the forward direction to deliver the treatment portion 20of the treatment device 18 from a distal opening 28 a of the outercatheter 14, toward the stenosed portion X of a left popliteal artery220 from the left femoral artery 218.

Thereafter, a treatment step in which the stenosed portion X is treatedby the treatment portion 20 of the treatment device 18 is performed.After the treatment step, the outer catheter 14 and the treatment device18 are pulled out of the body of the patient 100 to end the interventionprocedure.

Next, the assembly 12 used for the treatment method and the sheathintroducer 22 used in the introduction step will be described in detailwith reference to FIG. 2.

As described above, the assembly 12 is configured such that the outercatheter 14 (first catheter) and the inner catheter 16 (second catheter)are layered on each other or axially overlap one another. The outercatheter 14 includes an outer shaft 24 that is in the form of a long(elongated) flexible tube and an outer catheter hub 26 that is disposedat the proximal side or end of the outer shaft 24. The outer catheterhub 26 is connected to the outer shaft 24.

The inside of the outer shaft 24 and the outer catheter hub 26 arepenetrated by an insertion lumen 28 (lumen) that is formed in the axisdirection. That is, the insertion lumen 28 extends axially through theouter catheter hub 26 and the outer shaft 24. The insertion lumen 28 isconnected to or opens to the distal opening 28 a in the distal end ofthe outer shaft 24 and to a proximal opening 28 b in the proximal end ofthe outer catheter hub 26. The inner catheter 16 is inserted into andpositioned in the insertion lumen 28.

The outer shaft 24 is configured such that the insertion lumen 28 has arelatively large inner diameter. The outer diameter of the outer shaft24 is about the same as the outer diameter of the conventional guidingcatheter introduced from the right radial artery 200. For example, theouter diameter of the outer shaft 24 is about 2.33 mm to 2.4 mm (7 Fr:1Fr is equal to ⅓ mm). The inner diameter of the insertion lumen 28 is,for example, equal to or smaller than 2.2 mm, though the inner diameterdepends on the outer diameter of the inner catheter 16 or the treatmentdevice 18. That is, the outer shaft 24 has a thin wall portion 24 a thatsurrounds the insertion lumen 28.

Moreover, a reinforcing wire 30 is embedded inside the wall portion 24 ato improve kink resistance, torque-transmitting properties, andoperability of the outer shaft 24. The reinforcing wire 30 is configuredas a braid or a coil. The reinforcing wire 30 is in the form of a thinplate-like band and wound in a coil (or a mesh) along thecircumferential direction of the wall portion 24 a. The reinforcing wire30 extends from a position, which is separated or spaced from the distalend of the outer shaft 24 at a predetermined interval or distance, to aconnection site of the outer catheter hub 26, and reinforces the entireouter shaft 24. Examples of the material constituting the reinforcingwire 30 include metals such as Ni—Ti-based alloys and stainless steel(all kinds of SUS), hard polymers such as polyolefin, liquid crystalpolymers, and the like.

It is preferable for the full length of the outer shaft 24 to be, forexample, equal to or greater than 150 cm, such that the distal end ofthe outer shaft 24 reaches the left femoral artery 218, although thefull length varies with the body size of the patient 100. The outercatheter hub 26 is firmly connected to the proximal portion of the outershaft 24 such that a surgeon can reliably operate the outer shaft 24using the outer catheter hub 26.

The outer catheter hub 26 has a diameter larger than that of the outershaft 24 such that the surgeon can relatively easily grip the hub. Astrain relief 26 a, which is configured to reduce a load applied to theportion in which the outer catheter hub 26 is connected to the outershaft 24, is disposed in the distal portion of the outer catheter hub26. Moreover, a pair of wings 26 b for improving operability for thesurgeon is disposed on the outer circumferential surface of the outercatheter hub 26.

A bump or enlargement 32 a forming one side of a lock mechanism 32 ofthe assembly 12 is located at the proximal portion of the outer catheterhub 26. The bump 32 a protrudes in the circumferential direction of theouter circumferential surface of the outer catheter hub 26, and ispushed into (mates with) a screw-like groove 32 b of an inner catheterhub 36 which will be described later. The enlargement 32 a and thescrew-like groove 32 b together form a luer lock.

Similar to the outer catheter 14, the inner catheter 16 includes aninner shaft 34 that is in the form of a long (elongated) flexible tubeand an inner catheter hub 36 that is disposed at the proximal side ofthe inner shaft 34. The inner catheter hub 36 is connected to the innershaft 34. The inside of the inner shaft 34 and the inner catheter hub 36is penetrated by a guide wire lumen 38 that is formed along the axisdirection. That is, the guide wire lumen 38 extends axially through theinner shaft 34 and the inner catheter hub 36. A guide wire 40 (see forexample FIG. 3) is inserted into the guide wire lumen 38. In a statewhere the assembly 12 has been established, the guide wire lumen 38constitutes the lumen of the assembly 12. Accordingly, it is preferableto configure the guide wire lumen 38 to have such a size that the guidewire 40 can slide inside the guide wire lumen 38 and the guide wirelumen 38 is not perfused with the blood (body fluid) flowing in a bloodvessel.

The full length of the inner shaft 34 is larger than the full length ofthe outer shaft 24. Accordingly, in a state where the inner shaft 34 isconnected to the assembly 12, and the proximal portion of the innershaft 34 is exposed from the proximal opening 28 b of the outer catheterhub 26, the inner shaft 34 can be exposed from the distal opening 28 aof the outer shaft 24 (i.e., the distal end portion of the inner shaft34 extends distally beyond the distal end of the outer shaft 24 as shownin FIG. 2).

An angled or turned distal end portion 34 b, which is angled or turns tomake it easier to guide the direction and the like of the assembly 12during the delivery step, is provided at the distal end of the innershaft 34. That is, the distal end portion of the inner shaft 34 isangled relative to the immediately adjoining portion of the inner shaft34 as shown in FIG. 2 so that the central axis of the angled portion 34b is disposed at an angle other than 0° and 180° with respect to theaxis of the portion of the inner shaft 34 immediately adjoining theangled portion 34 b. It is preferable for the outer circumferentialsurface of the angled or turned distal end portion 34 b to be coatedwith a hydrophilic polymer such that the inner shaft 34 can excellentlyslide inside the blood vessel 102 (see FIG. 3). Moreover, it ispreferable for a reinforcing wire (braid) 42 for reinforcing the innershaft 34 to be embedded in a wall portion 34 a of the inner shaft 34that is separated (spaced) from the angled or turned distal end portion34 b of the inner shaft 34 at a predetermined interval or predetermineddistance.

When the inner diameter of the insertion lumen 28 is about 2.2 mm, theouter diameter of the inner shaft 34 is preferably, for example, about2.1 mm (6 Fr), even though the outer diameter also depends on the innerdiameter of the insertion lumen 28 of the outer shaft 24. Moreover, whenthe inner diameter of the insertion lumen 28 is about, for example, 1.7mm, the outer diameter of the inner shaft 34 is preferably about 1.5 mmto 1.6 mm (5 Fr).

It is preferable for the outer shaft 24 or the inner shaft 34 to haverigidity and flexibility such that the shaft can rather excellently moveforward and backward inside the meandering blood vessel 102 during thedelivery step. Examples of materials constituting the outer shaft 24 orthe inner shaft 34 include resins and metals. Examples of the resinsinclude polymer materials such as polyolefin (for example, polyethylene,polypropylene, polybutene, an ethylene-propylene copolymer, anethylene-vinyl acetate copolymer, an ionomer, a mixture composed of twoor more kinds of these, and the like), polyvinyl chloride, polyamide, apolyamide elastomer, polyester, a polyester elastomer, polyurethane, apolyurethane elastomer, polyimide, and a fluororesin, a mixture ofthese, and a combination of two or more kinds of the above polymermaterials. Examples of the metals include pseudoplastic alloys(including super elastic alloys) such as Ni—Ti-based alloys,shape-memory alloys, stainless steel (for example, all kinds of SUS suchas SUS304, SUS303, SUS316, SUS316L, SUS316J1, SUS316J1L, SUS405, SUS430,SUS434, SUS444, SUS429, SUS430F, and SUS302), cobalt-based alloys, noblemetals such as gold, platinum, tungsten-based alloys, carbon-basedmaterials (including a piano wire), and the like. It is also possible touse a complex or combination of the resins or metals (for example, amultilayer tube obtained by lamination, and the like). Moreover, aradiopaque maker that can be confirmed by radiography may be placed in aportion near the distal end of the outer shaft 24 or the inner shaft 34.

The inner catheter hub 36 connected to the inner shaft 34 is in the formof a cylinder having an outer diameter which is almost the same as thatof the outer catheter hub 26. A connector cylinder portion 44, whichsurrounds the periphery of a connection projection 36 a connected to theinner shaft 34, is disposed in the distal portion of the inner catheterhub 36. The connector cylinder portion 44 forms the other side of thelock mechanism 32. On the inner circumferential surface of the connectorcylinder portion 44, the screw-like or helical groove 32 b into whichthe bump 32 a of the outer catheter hub 26 is screwed is formed.

That is, in the assembly 12, the proximal portion of the outer catheterhub 26 is connected and fixed to (locked with) the distal portion of theinner catheter hub 36 by the lock mechanism 32, whereby a singleoperation portion that can operate two catheters can be performed. Asurgeon grips the outer catheter hub 26 or the inner catheter hub 36 andoptionally performs an advance and retreat operation or a rotationoperation. In this way, the surgeon can integrally perform the advanceand retreat operation or the rotation operation of the outer shaft 24 orthe inner shaft 34. By rotating the inner catheter hub 36 relative tothe outer catheter hub 26, the lock mechanism 32 can be comparativelyeasily separated (released).

Before the introduction step is performed, the assembly 12 isestablished in a state where the inner catheter 16 is inserted into(positioned inside) the insertion lumen 28 of the outer catheter 14, andmovement of both the catheters in the axial direction is restricted bythe lock mechanism 32. In the introduction step, the assembly 12 isinserted into the wrist 108 of the patient 100 through the sheathintroducer 22.

The sheath introducer 22 includes a flexible tubular sheath 46 and anintroducer hub 48 which is connected to the proximal portion of thesheath 46. The inside of both the sheath 46 and the introducer hub 48 ispenetrated by a guiding lumen 50 that extends along the axial direction.That is, the guiding lumen 50 passes through both the sheath 46 and theintroducer hub 48. The guiding lumen 50 is connected to (opens to) adistal opening 50 a (see FIG. 3) at the distal end of the sheath 46 andto a proximal opening 50 b at the proximal end of the introducer hub 48.A dilator is first introduced into the guiding lumen 50 to make apuncture in the wrist 108 of the patient 100. After the dilator iswithdrawn, the assembly 12 is inserted into the guiding lumen 50 of thesheath introducer 22.

The sheath 46 is inserted into the right radial artery 200 in theintroduction step so as to promote introduction of the assembly 12. Thefull length of the sheath 46 is shorter than that of the outer shaft 24or the inner shaft 34, and is about, for example, 10 cm to 30 cm.Moreover, the outer diameter of the sheath 46 is about, for example, 2.7mm (8 Fr), that is, equal to or smaller than 2.8 mm, such that it can beinserted into the right radial artery 200 having a vessel diameter ofabout 2.9 mm±0.6 mm.

The material constituting the sheath 46 is not particularly limited, andfor example, it is possible to use a polymer composition containing acrystalline polymer, such as polyether ether ketone (PEEK), polyetherketone (PEK), polyether ketone ketone (PEKK), polyether ether ketonketone (PEEKK), polyphenylene sulfide (PPS), polyether sulfone (PES),polysulfone (PSF), polyimide (PI), polyether imide (PEI), and amorphouspolyarylate (PAR). Other resin materials may also be used, and forexample, an ethylene tetrafluoroethylene (ETFE) copolymer is suitablefor making a thin sheath 46, since it has excellent strength and iseasily processed.

Therefore, a wall portion 46 a of the sheath 46 constituting the guidinglumen 50 is thin wall portion having a thickness of about 0.1 mm to 0.15mm for instance. Consequently, the inner diameter of the guiding lumen50 can be increased, and as the outer catheter 14 (assembly 12), asufficiently thick catheter (7 Fr) can be used according to the size ofthe guiding lumen 50. The distal end of the sheath 46 is tapered to thetip, and accordingly, a step difference formed between the sheath 46 andthe assembly 12 or the dilator sent from the distal opening 50 a can bereduced.

The introducer hub 48 has a diameter that is larger than that of thesheath 46, so as to make it easy for a surgeon to grip the hub and tofacilitate introduction of the assembly 12. A port 48 a that is incommunication with the guiding lumen 50 is located on the lateralcircumferential surface of the introducer hub 48. The port 48 a isconnected to a tube 51 having a connector 51 a (three-way cock) that iswidely used. The sheath introducer 22 can guide a liquid such asphysiological saline to the guiding lumen 50 through the connector 51 a.It is preferable for the guiding lumen 50 of the introducer hub 48 to beprovided with a valve for preventing leakage of the blood to theoutside.

The assembly 12 and the sheath introducer 22 of the intervention device10 are configured, by way of example, in the manner described above. Inthe treatment device 18 of the intervention device 10 shown in FIG. 1,the full length of a treatment device side shaft 52 that is insertedinto the outer shaft 24 is long. Except for this point, a known devicecan be used as the treatment device 18. For example, the treatmentportion 20 disposed in the distal portion of the treatment device sideshaft 52 of the treatment device 18 has a stent 54 that will remain inthe stenosed portion X and a balloon 56 that can be dilated or expandedinside the stent 54 (see FIG. 5C). That is, this example of thetreatment device 18 is configured as a stent delivery device that cancause the stent 54 to dilate and remain in the stenosed portion X. Thestent is an example of an intraluminal prosthesis.

Referring to the intervention device 10 configured by way of example inthe manner described above, a treatment method according to a firstembodiment will be described in detail.

In the following description, a treatment method for treating theaforementioned stenosed portion X of the left popliteal artery 220 ofthe left leg 104 b will be explained in detail. But the treatment targetof the treatment method is not particularly limited. For example,arteries such as the left femoral artery 218, a left anterior tibialartery 222, and a left posterior tibial artery 224 or a peripheral bloodvessel 226 connected to an artery may be the treatment site.Alternatively, in addition to arteries, veins may also be treated.Furthermore, blood vessels of the right leg 104 a (a right femoralartery 230, a right popliteal artery 232, a right anterior tibial artery234, a right posterior tibial artery 236, and the like) may also betreated. To summarize, the treatment site can include various lumens inthe lower limb 104. Moreover, in addition to the stenosed portion X,various diseases that can be treated by the treatment device 18 in anintervention procedure, such as occluded portions and damage or aneurysmof blood vessels, can be the lesion as a treatment target.

Before implementing the treatment method, a surgeon determines inadvance an introduction portion Y of the blood vessel 102 of the arm106, and prepares the intervention device 10 (the assembly 12, thetreatment device 18, and the guide wire 40) having a length appropriatefor the introduction portion Y.

Herein, a case where the wrist 108 (right radial artery 200) of theright arm 106 a is selected as the introduction portion Y will bedescribed. However, the introduction portion Y is not limited to thissite. For example, instead of the right radial artery 200, a right ulnarartery 201 in the wrist 108 of the right arm 106 a may be selected. Whenthe wrist 108 (the right radial artery 200 or the right ulnar artery201) is selected as the introduction portion Y, it is possible to obtainadvantages of being able to bend an elbow after the treatment, to rathereasily arrest hemorrhage, to shorten a resting period, and the like.

As shown in FIG. 1, a portion near the elbow of the right arm 106 a maybe selected as an introduction portion Y′, and the assembly 12 isdirectly introduced into the right brachial artery 202. The rightbrachial artery 202 is connected to the right radial artery 200 and theright ulnar artery 201. For this reason, the vessel diameter of theright brachial artery 202 is larger than that of the right radial artery200 and the like, hence the assembly 12 or the sheath introducer 22having a larger diameter can be inserted into the right brachial artery202. Moreover, in consideration of the better arm and the like of thepatient 100, the introduction portion Y′ may be set in the wrist 108(left radial artery or left ulnar artery) or a portion near the elbow(left brachial artery) of the left arm 106 b. To summarize, theintroduction portions Y and Y′ of the intervention device 10 may beoptionally set in an appropriate site in both arms, in consideration ofdelivery of the assembly 12 to the stenosed portion X, postoperativecare for the patient 100, and the like.

After selecting an assembly 12 that is appropriate for the determinedintroduction portion Y, a surgeon inserts the inner catheter 16 into theinsertion lumen 28 of the outer catheter 14, and assembles the assembly12 such that the angled or turned distal end portion 34 b of the innercatheter 16 protrudes from (beyond) the distal opening 28 a of the outercatheter 14. That is, the assembly 12 is configured with two cathetersin which the axial center of the insertion lumen 28 and the axial centerof the guide wire lumen 38 are in an approximately coaxial position(supply step). At this time, the screw-like groove 32 b of the innercatheter hub 36 and the bump 32 a of the outer catheter hub 26 arescrewed together (locked with each other), whereby the assembled stateof the assembly 12 is maintained. The assembly 12 may be assembled inadvance when it is supplied as a product.

In the introduction step, the surgeon locates the right radial artery200 on the wrist 108 of the right arm 106 a, and inserts the guide wire40 into the artery by making a puncture or an incision in the rightradial artery 200 by a known technique such as Seldinger technique. Thatis, as shown in FIG. 3, in a state where a hand is held palm up, theguide wire 40 is inserted into the right radial artery 200, and adilator of the sheath introducer 22 is inserted into the artery alongthe guide wire 40. The outer circumferential surface of the dilator iscovered by the sheath 46 of the sheath introducer 22. When the dilatoris inserted, the sheath 46 is also inserted into the right radial artery200 together with the dilator. As described above, the diameter of thesheath 46 is smaller than the vessel diameter of the right radial artery200. Accordingly, the sheath 46 can relatively easily advance into theright radial artery 200.

After causing the distal portion of the sheath 46 to advance by apredetermined distance to the central side (anatomically-based) terms ofthe right radial artery 200, the surgeon pulls out the dilator, andinserts the assembly 12 into the artery from the proximal opening 50 bof the introducer hub 48. At this time, the surgeon inserts the guidewire 40, which has already been inserted into the guide wire lumen 38 ofthe inner catheter 16, into the artery so as to cause the assembly 12 toadvance along the guide wire 40. Since the wall portion 46 a of thesheath 46 is thin, the guiding lumen 50 has an inner diameter that canrather easily assist the advance (sliding) of the assembly 12 (outercatheter 14). That is, the assembly 12 is smoothly sent from (advancedbeyond) the distal opening 50 a of the sheath 46 and advances inside theright radial artery 200.

As shown in FIG. 1, the surgeon causes the assembly 12 to advance alongthe guide wire 40 ahead, in the delivery step. At this time, whilechecking the state of the distal portion 12 a of the assembly 12 shownin a radiographic image obtained by radiography, the surgeon grips andoperates the proximal side (proximal end portion) of the assembly 12exposed from the introducer hub 48. As a result, a distal portion 12 aof the assembly 12 moves into the right brachial artery 202 from theright radial artery 200, makes an advance along the right subclavianartery 204 as if making a curve or turn, and advances into the aorta(aortic arc 208) through the brachiocephalic artery 206.

After the distal portion 12 a of the assembly 12 advances into theaortic arc 208, the surgeon rotates the proximal side of the assembly 12under radiography, and moves the distal portion 12 a of the assembly 12to the thoracic aorta 210. Since the angled or turned distal end portion34 b of the inner catheter 16 forms a slope or angle with respect to theaxial direction of the assembly 12, the distal portion 12 a of theassembly 12 having advanced from the brachiocephalic artery 206 can berelatively easily brought close to the thoracic aorta 210 as shown inFIG. 4A.

While the distal portion 12 a of the assembly 12 is moving toward thethoracic aorta 210, the surgeon further pushes the proximal side (end)of the assembly 12. As a result, the distal portion 12 a of the assembly12 moves from the central side to the peripheral side along the aorta(the thoracic aorta 210 and the abdominal aorta 212), and reaches aconnection position Z between a right common iliac artery 228 and theleft common iliac artery 214 at the peripheral side of the abdominalaorta 212. As shown in FIG. 4B, even in this connection position Z, ifthe proximal side of the assembly 12 is rotated, the angled or turneddistal end portion 34 b can be moved in a desired direction (left commoniliac artery 214). Thereafter, by pushing (forwardly moving) theproximal side of the assembly 12, the surgeon causes the distal portion12 a of the assembly 12 to advance to the left external iliac artery 216and the left femoral artery 218 from the left common iliac artery 214.

When a full length catheter which is simply lengthened is inserted fromthe arm 106 and caused to advance to the blood vessel 102 of the lowerlimb 104, most of the catheter is inserted into the body, and so theoperability of the catheter deteriorates. That is, even if the proximalside of the catheter that is exposed outside the body is operated, theouter circumferential surface of the catheter comes into contact with,for example, the blood vessel 102. Accordingly, the operating force isnot easily transmitted to the distal portion, and this can cause greatdifficulty in delivering the catheter to the lower limb 104.

In contrast, using the assembly 12 constituted with double catheters(two catheters) as described in the treatment method according to thefirst embodiment, the distal portion 12 a of the assembly 12 can be moreeasily delivered to the blood vessel 102 of the lower limb 104. That is,in the assembly 12, the inner catheter 16 accommodated in the insertionlumen 28 of the outer catheter 14 reinforces the entire assembly 12.Accordingly, for example, even when the outer catheter 14 is pressed bythe blood vessel 102, the inner catheter 16 can excellently support theouter catheter 14.

Particularly, with the assembly 12 disclosed here, even when arelatively strong frictional force is applied to the outer catheter 14from the blood vessel 102, the outer circumferential surface of theinner catheter 16 comes into contact with the wall portion 34 a of theouter catheter 14 with a strong frictional force when the catheter isrotated. Therefore, in addition to the torque of the outer catheter 14,the torque of the inner catheter 16 is also transmitted, wherebyrotation of the entire assembly 12 is promoted. As a result, in theassembly 12, torque is transmitted to the distal portion 12 a to ahigher degree.

Alternatively, when it is desired to change the course of the assembly12, the surgeon may rotate only the inner catheter 16 without alsorotating the outer catheter 14. In this manner, the angled or turneddistal end portion 34 b of the inner catheter 16 rotated relative to thefixed outer catheter 14 moves in a desired direction. As a result, theproperties required at the time of delivering the assembly 12 arefurther improved.

As shown in FIG. 5A, in the delivery step, the distal portion 12 a ofthe assembly 12 is delivered to a predetermined position (position nearthe portion above the left popliteal artery 220) of the left femoralartery 218, and delivery of the assembly 12 is then stopped. The leftpopliteal artery 220 has a vessel diameter smaller than that of the leftfemoral artery 218 and meanders quite a lot. Accordingly, if theassembly 12 is stopped in the left femoral artery 218, it is possible toprevent the blood vessel 102 from applying a heavy load to the outercatheter 14.

The point in time when the delivery step is stopped (the position wherethe distal portion 12 a of the assembly 12 is stopped) is notparticularly limited, and may be optionally changed by the surgeon inthe middle of the procedure, according to the treatment condition ortreatment target. For example, in the delivery step, the distal portion12 a of the assembly 12 may be delivered to a portion near the knee ofthe patient 100 (for example, the popliteal artery), portion below thepatient's knee (for example, the anterior tibial artery or the posteriortibial artery), or the patient's ankle (the fibular artery or thedorsalis pedis artery). If the distal portion 12 a is delivered to theabove position, the treatment target formed in the portion near thepatient's knee, the portion below the patient's knee or ankle can beexcellently treated by the treatment device 18 which will be deliveredthereto later. Moreover, depending on the treatment target, for example,the distal portion 12 a of the assembly 12 may be stopped at the iliacartery (the left common iliac artery 214 or the left external iliacartery 216). That is, in the present specification, the “blood vessel oflower limb” also includes the blood vessels (the iliac artery and thelike) closer to the peripheral side than to the abdominal aorta 212.

In the pull-out step performed after the delivery step, the innercatheter hub 36, having been connected to the outer catheter hub 26 bythe lock mechanism 32, is unlocked. That is, the two cathetersconstituting the assembly 12 are disassembled. Thereafter, as shown inFIG. 5B, the position of the outer catheter 14 and the guide wire 40 inthe axial direction with respect to the left femoral artery 218 isfixed, and only the inner catheter 16 is caused to retreat or moverearwardly so that the inner catheter is removed from the outer catheterand the patient. As a result, only the outer catheter 14 is left in thebody of the patient 100. As described above, in the outer catheter 14,the reinforcing wire 30 is embedded in the wall portion 24 a of theouter shaft 24 so as to reinforce the shaft. Therefore, even after thepull-out step, the outer catheter 14 can maintain the insertion lumen 28in an excellent state.

In the device advance step performed after the pull-out step, thesurgeon inserts the distal end of the treatment device 18 (stentdelivery device) into the proximal opening 28 b of the outer catheter14. At this time, the surgeon inserts the guide wire 40 into thetreatment device 18, and causes the treatment device 18 to advance alongthe insertion lumen 28 of the outer catheter 14 and the guide wire 40.As a result, the treatment portion 20 of the treatment device 18 isdelivered to the distal side (end) of the outer catheter 14 as shown inFIG. 5C.

As shown in FIG. 5D, after the treatment portion 20 is sent (moved) tothe left femoral artery 218 after moving beyond the distal opening 28 aof the outer catheter 14, the surgeon continues to advance the treatmentportion 20. The shaft 52 at the treatment device side moves under theguidance of the outer shaft 24, and as a result, the treatment device 18relatively easily enters the left popliteal artery 220. Thereafter, byway of radiography, the surgeon checks the state where the treatmentportion 20 has been delivered to the position matching the stenosedportion X, and ends the device delivery step when the treatment portion20 is at the stenosed portion.

Subsequently, in the treatment step, the surgeon provides treatment bywhich the stenosed portion X of the left popliteal artery 220 expands.Specifically, as shown in FIG. 6A, the surgeon positions the treatmentportion 20 such that the treatment portion 20 is located at the positionof the stenosed portion X in the axial direction so that the treatmentportion 20 is positioned inside the stenosed portion 20. Next, as shownin FIG. 6B, the surgeon dilates the balloon 56, such that the stent 54around the balloon 56 dilates in the radial outward direction of theleft popliteal artery 220. As a result, the stent 54 dilates and expandsa blood vessel wall 102 a of the left popliteal artery 220, andmaintains the dilated state. After the stent 54 dilates, the balloon 56contracts again as shown in FIG. 6C, and the treatment device 18retreats (is moved rearwardly).

That is, since the dilated stent 54 remains in the left popliteal artery220 (stenosed portion X), dilation of the artery in the radial directionis supported, and the blood flows smoothly inside the stent 54. Thestent 54 may be an indwelling drug eluting stent. For example, byfunctioning as a drug eluting stent that suppresses restenosis, thestent 54 can keep the blood vessel 102 dilated continuously.

In the treatment method according to the first embodiment, the treatmentdevice 18 for treating the treatment target is not limited to the stentdelivery device, and various modified examples and application examplescan be adopted. Hereinafter, several examples of the treatment device 18in other forms will be described.

In a treatment method according to a first modified example shown inFIG. 7A, a treatment portion 20A of a treatment device 18A includes aballoon 60. After being delivered to the treatment target (for example,the stenosed portion X) by the treatment device advance step, theballoon 60 is dilated in the radial outward direction by a dilationoperation performed by the surgeon. As a result, the blood vessel 102 ofthe stenosed portion X expands, whereby blood flow becomes smooth.

In a treatment method according to a second modified example shown inFIG. 7B, a treatment device 18B is configured with a drug applyingdevice 18B (Drug Eluting Balloon catheter: DEB). The drug applyingdevice 18B is sometimes used, for example, in the case where damage Xαsuch as cracks is formed in the blood vessel wall 102 a of the bloodvessel 102 as a treatment target by percutaneous transluminalangioplasty (PTA) or the like. The treatment portion 20B of the drugapplying device 18B is configured to include a balloon 58 which dilatesto a size approximately the same as or slightly smaller than the innerdiameter of the blood vessel 102 with the damage Xα. The lateralcircumferential surface of the balloon 58 is coated with a drug 58 a fortreating the damage Xα. The drug applying device 18B can apply the drug58 a to the damage Xα by using the dilated balloon 58.

In a treatment method according to a third modified example shown inFIG. 7C, a treatment portion 20C of a treatment device 18C includes acutter portion 62 (atherectomy device) that scrapes off an atheroma(plaque). For example, after being delivered to the treatment target bythe treatment device advance step, the cutter portion 62 rotates on theaxis of the treatment device side shaft 52 based on the operationperformed by the surgeon, and treats the target by removing the atheromaaround the cutter portion 62.

In a treatment method according to a fourth modified example shown inFIG. 7D, a treatment device 18D is for treating an aneurysm Xβ(treatment target) formed in the blood vessel 102. The treatment device18D has, as a treatment portion 20D, an indwelling device/substancesending portion 66 for filling the aneurysm Xβ with an indwellingdevice/substance 64 (for example, a coil). After being delivered intothe aneurysm Xβ (or to an opening portion of the aneurysm Xβ) by thetreatment device advance step, the indwelling device/substance sendingportion 66 fills the aneurysm Xβ with the indwelling device/substance 64based on the operation performed by the surgeon, thereby treating thetarget by blocking the aneurysm Xβ.

As another treatment device 18 applicable to the treatment target, forexample, an aspiration mechanism that aspirates thrombi and the likeconstituting the stenosed portion X can be used.

In a treatment method according to a fifth modified example shown inFIGS. 8A to 8C, a guiding catheter 70 (third catheter) is sent out ofthe outer catheter 14. The guiding catheter 70 accommodates thetreatment device 18 in an accommodating space 72 (lumen) inside theguiding catheter 70. At a stage in which the guiding catheter 70 hasmade an advance inside the blood vessel 102 to a certain extent, thecatheter can send out the treatment device 18. The treatment device 18can adopt various configurations described above, such as a stentdelivery device.

The aforementioned treatment method is particularly effective when atreatment target X is in a peripheral blood vessel 226 smaller than theartery. Hereinafter, a specific example of the treatment method will bedescribed. In this case, to the pull-out step in which the innercatheter 16 is pulled out of the outer catheter 14 of the assembly 12delivered to the left femoral artery 218, the same method as describedabove can be adopted. After the pull-out step, as shown in FIG. 8A, thesurgeon performs the catheter advance step in which the guiding catheter70 is caused to advance along the insertion lumen 28 of the outercatheter 14.

In the catheter advance step, the guiding catheter 70 is sent out of(advanced beyond) the distal opening 28 a of the outer catheter 14.Moreover, as shown in FIG. 8B, the guiding catheter 70 is caused toadvance, and the distal portion of the guiding catheter 70 is deliveredto a portion near the opening portion of the peripheral blood vessel226. Subsequently, in the same manner as in the aforementioned treatmentdevice advance step, the treatment device 18, which has beenaccommodated in advance in the accommodation space 72 of the guidingcatheter 70, is sent out of (advanced beyond) the distal end of theguiding catheter 70 and delivered to the treatment target X of theperipheral blood vessel 226. Thereafter, the treatment step in which thetreatment target X is treated by the treatment portion 20 of thetreatment device 18 is performed.

As described above, by sending the guiding catheter 70 out of the outercatheter 14, the treatment device 18 can be delivered to various bloodvessels 102 present in the lower limb 104. Particularly, although theblood vessel 102 closer to the peripheral side than to the leftpopliteal artery 220 meanders quite a lot, the guiding catheter 70having a diameter smaller than that of the outer catheter 14 excellentlyadvances to a portion near the treatment target of the peripheral bloodvessel 226. As a result, the treatment device 18 can be rather easilydelivered to the treatment target.

The third catheter that is delivered to the treatment target X throughthe inside of the outer catheter 14 is not limited to the guidingcatheter 70 and can be configured or constituted in various ways. Forexample, as the third catheter, an angiographic catheter for performingangiography inside a blood vessel, a microcatheter for treating smallerblood vessels, and the like can be used. Moreover, depending on thetreatment method, the inner catheter 16 as a second catheter may becaused to advance without being pulled out (without performing thepull-out step), and the treatment device 18 may be guided through theinside of the inner catheter 16. Even in this case, it is possible tomake the treatment device 18 pass through the lumen (inside) of theouter catheter 14.

As described above, in the treatment method according to the firstembodiment, by using the assembly 12 constituted with double catheters(two catheters), the distal portion 12 a of the assembly 12 can be moreeasily delivered to the blood vessel 102 of the lower limb 104. That is,the assembly 12 has a double structure composed of the outer catheter 14and the inner catheter 16, and accordingly, the properties (kinkresistance, torque-transmitting properties, operability, and the like)required at the time of delivery are improved. As a result, even whenthe assembly 12 is long enough to reach the lower limb 104 from the arm106, it is relatively easy for the surgeon to operate the distal portion12 a of the assembly 12 and to cause the distal portion 12 a to advanceinside a blood vessel. Consequently, the surgeon can provide treatmentby efficiently disposing the outer catheter 14 in a predeterminedposition and smoothly and accurately delivering the treatment device 18to the treatment target through the outer catheter 14.

Moreover, since the sheath 46 having an outer diameter of 2.8 mm isused, a quite thick catheter (for example, a catheter having an outerdiameter of around 2.4 mm) can be used as the outer catheter 14, andaccordingly, the properties required at the time of delivery can befurther improved.

In the delivery step, the distal portion 12 a of the assembly 12 ispositioned in the left femoral artery 218. Accordingly, in the deviceadvance step, the outer catheter 14 can assist (guide) the advance ofthe treatment device 18. The diameter of the treatment device 18 issmaller than that of the outer catheter 14, and as a result, thetreatment device 18 can excellently advance inside the left poplitealartery 220 that relatively meanders much. Furthermore, even when thetreatment target is present in a portion near the knee, the calf, or aportion near the ankle, the properties required at the time ofdelivering the catheter assembly 12 having a double structure can bemaintained. Therefore, the treatment device 18 can be smoothlydelivered.

In addition, by the lock mechanism 32, the outer catheter 14 and theinner catheter 16 are fixed to (locked with) each other. Accordingly,when operating the assembly 12, the surgeon can integrally operate theouter catheter 14 and the inner catheter 16. As a result, the propertiesrequired at the time of delivering the assembly 12 inserted into theblood vessel 102 can be further improved.

Next, a treatment method according to a second embodiment will bedescribed with reference to FIGS. 9A to 10B. The treatment methodaccording to the second embodiment is a procedure for treating treatmenttargets (hereinafter, described as “right stenosed portion X1” and “leftstenosed portion X2”) in both the lower limbs (a right leg 104 a and aleft leg 104 b) of the patient 100. The intervention device 10 used inthis treatment method is basically the same as the intervention device10 of the first embodiment.

In the following description, a sequence will be described in which theleft stenosed portion X2 is first treated similar to the firstembodiment, and then the right stenosed portion X1 is treated. In thiscase, for treating the left stenosed portion X2, the procedure from theintroduction step to the treatment step can be performed. Moreover, theorder of treating the right leg 104 a and the left leg 104 b can beoptionally determined by the surgeon.

In the treatment method according to the second embodiment, after thetreatment step for left stenosed portion X2 ends, as shown in FIG. 9A, adevice retreat step is performed in which the treatment device 18 havingbeen used for treating the left stenosed portion X2 is caused to retreatfrom the outer catheter 14. As a result, the treatment device 18 ispulled out of the outer catheter 14, and the outer catheter 14 and theguide wire 40 remain in the body of the patient 100.

Thereafter, as shown in FIG. 9B, the surgeon performs a retreat step inwhich the distal portion of the outer catheter 14 is caused to retreatto the connection position Z between the right common iliac artery 228and the left common iliac artery 214. As a result, the distal portion ofthe outer catheter 14 positioned in the left femoral artery 218 retreatsto the peripheral side (connection position Z) of the abdominal aorta212 through the left external iliac artery 216 and the left common iliacartery 214. At this time, the guide wire 40 is also caused to retreat.

After the retreat step, as shown in FIG. 10A, the surgeon performs astep of delivery to an individual site in which the outer catheter 14 isdelivered from the peripheral side of the abdominal aorta 212 to apredetermined position of the right femoral artery 230 of the right leg104 a. At this time, led by the guide wire 40, the outer catheter 14 iscaused to advance and be delivered inside the right common iliac artery228, a right external iliac artery 229, and a right femoral artery 230.In the step of delivery to an individual site, depending on the state ofthe blood vessel 102 of the patient 100 (for example, a state where theblood vessel meanders much, a state where the blood vessel is small, andthe like), the inner catheter 16 may be reinserted into the outercatheter 14, and the assembly 12 may be reestablished. As a result, thedistal portion 12 a of the assembly 12 can be delivered to the rightfemoral artery 230, similarly to the case where it is delivered to theleft femoral artery 218.

After the step of delivery to an individual site, as shown in FIG. 10B,the surgeon performs a step of causing a treatment device to advance toan individual site in which a treatment device 80 (device for treatingan individual site) for treating the right stenosed portion X1 of theright leg 104 a is caused to advance. As the treatment device 80, adevice in which the stent 54 that will remain in the right stenosedportion X1 is disposed in a treatment portion 80 a is used. Thetreatment device 80 is caused to advance through the insertion lumen 28of the outer catheter 14 and sent out of (advanced beyond) the distalopening 28 a of the outer catheter 14 to the right femoral artery 230.After the treatment device 80 is sent to the right femoral artery 230,the treatment portion 80 a is delivered to a site (right poplitealartery 232) where the right stenosed portion X1 is present.

Thereafter, an individual site treatment step in which the rightstenosed portion X1 is treated by the treatment device 80 is performedin the right stenosed portion X1. In the individual site treatment step,due to dilation of the balloon 56 of the treatment portion 80 a of thetreatment device 80, the stent 54 dilates, whereby the right stenosedportion X1 expands. As a result, the stent 54 remains in the rightstenosed portion X1 to maintain the dilated state, and treatment of theright stenosed portion X1 ends.

As described above, according to the treatment method of the secondembodiment, when a treatment target is present in both the lower limbs104, the intervention procedure can be consecutively performed. That is,after the treatment target in one of the lower limbs 104 is treated, theouter catheter 14 is caused to retreat to the peripheral side of theabdominal aorta 212 and then caused to advance to the treatment targetof the other lower limb 104. In this manner, plural treatment targetspresent in different sites can be treated by a single treatment.

As a modified example (sixth modified example) of the treatment methodaccording to the second embodiment, before the individual site treatmentstep, a step of causing a catheter to advance to an individual site maybe performed in which the distal end of a guiding catheter 82 (thirdcatheter) is caused to advance. For example, as shown in FIGS. 11A to11C, when the right stenosed portion X1 is present in the peripheralblood vessel 226 connected to the right popliteal artery 232 of theright leg 104 a, the distal portion of the guiding catheter 82 isdelivered to a portion near the right stenosed portion X1 through theinsertion lumen 28 of the outer catheter 14. Thereafter, the treatmentdevice 18 is sent out of (advanced beyond) the distal portion of theguiding catheter 82, whereby a treatment portion 80 a of the treatmentdevice 80 can be excellently delivered to the right stenosed portion X1.

Next, a treatment method according to a third embodiment will bedescribed with reference to FIGS. 12 to 29. The treatment methodaccording to the third embodiment is basically a procedure that treatsthe same treatment target as being treated in the first embodiment. Inthis treatment method, an intervention device (for example, a catheterassembly 10 x of FIG. 12) different from the intervention device 10 usedin the first and second embodiments can be used.

In the following description, the intervention device used in thetreatment method of the third embodiment will first be described. Forthe sake of description and clearer understanding, the dimensional ratioof the drawings may be magnified and may thus differ from the actualratio in some cases. In the following description, the side of thecatheter assembly close to the surgeon is called “proximal side”(proximal end), and the side inserted into the body is called “distalside” (distal end).

As shown in FIGS. 12, 13A and 13B, the catheter assembly 10 x accordingto the third embodiment disclosed here has a double structure composedof an outer catheter 20 x and an inner catheter 30 x. The catheterassembly 10 x is percutaneously inserted into the radial artery, thebrachial artery, the femoral artery, and the like. The distal end of thecatheter assembly 10 x is caused to reach a target site through a bloodvessel, such that a catheter for treatment such as a balloon catheter orvarious liquids such as a contrast agent, a drug solution, andphysiological saline are introduced into a target site. Moreover, in theintervention procedure in which a catheter is introduced from the arteryof an arm to treat a lower limb, the catheter assembly 10 x is insertedinto the artery (the radial artery or the brachial artery) of an arm.

The outer catheter 20 x has a tubular outer catheter body 40 x, an outercatheter hub 50 x fixed to the proximal end of the outer catheter body40 x, and an anti-kink protector 60 x.

The inner catheter 30 x has an inner catheter body 31 x that isconfigured to be inserted into the outer catheter body 40 x, and aninner catheter hub 90 x that is disposed at the proximal end of theinner catheter body 31 x. The inner catheter hub 90 x is connected tothe proximal end of the inner catheter body 31 x. The inner catheterbody 31 x includes a linear shaft 70 x that is configured to be insertedinto the outer catheter body 40 x, and a tubular body 80 x that isdisposed in the distal end of the shaft 70 x. The tubular body 80 x isconnected to the distal end of the shaft 70 x.

When the distal side of the tubular body 80 x is inserted into theproximal side of the outer catheter hub 50 x, and the outer catheter hub50 x and the inner catheter hub 90 x come into contact with and areconnected to each other and fixed by a lock mechanism which will bedescribed later, the outer catheter 20 x is assembled with the innercatheter 30 x (assembled state) as shown in FIG. 12. If the outercatheter hub 50 x and the inner catheter hub 90 x can be connected toeach other, the lock mechanism does not have to be provided. Moreover, aslit, through which a guide wire can pass into and out of the catheterassembly, may extend from the distal end to the proximal end of theinner catheter hub 90 x. According to the above construction orconfiguration, in the state where the guide wire is inserted in thecatheter assembly 10 x, a surgeon can rather easily withdraw the innercatheter while remaining the guide wire and the outer catheter 20 x inthe body lumen.

First, the outer catheter 20 x will be described. As shown in FIGS. 13and 14, the outer catheter body 40 x is in the form of a flexible tube,and in the portion which approximately corresponds to the center of theouter catheter body 40 x, an outer catheter lumen 41 x which is as longas the full length of the outer catheter body 40 x is formed. The outercatheter lumen 41 x thus extends along the entire length of the outercatheter body 40 x.

The outer catheter body 40 x has an inner layer 42 x that forms an innersurface of the outer catheter lumen 41 x, an outer layer 43 x that formsthe outer surface, a reinforcing layer 44 x between the inner layer 42 xand the outer layer 43 x, and a highly flexible soft tip 45 x disposedat the distal side of the inner layer 42 x, the reinforcing layer 44 x,and the outer layer 43 x as shown in FIG. 15.

The outer layer 43 x has a first area 431 x positioned on the proximalside of the soft tip 45 x, a second area 432 x positioned on theproximal side of the first area 431 x, a third area 433 x positioned onthe proximal side of the second area 432 x, and a fourth area 434 xpositioned on the proximal side of the third area 433 x. Morespecifically, the first area 431 x is positioned immediately axiallyadjacent the soft tip 45 x on the proximal side of the soft tip 45 x,the second area 432 x is positioned immediately axially adjacent thefirst area 431 x on the proximal side of the first area 431 x, the thirdarea 433 x is positioned immediately axially adjacent the second area432 x on the proximal side of the second area 432 x, and the fourth area434 x is positioned immediately axially adjacent the third area 433 x onthe proximal side of the third area 433 x. The proximal end of thefourth area 434 x is fixed to the outer catheter hub 50 x. The thirdarea 433 x is more flexible than the fourth area 434 x, the second area432 x is more flexible than the third area 433 x, and the first area 431x is more flexible than the second area 432 x.

In the outer catheter body 40 x, an area from the distal portion of thefourth area 434 x to the soft tip 45 x forms a rigidity transitionportion 401 x in which the rigidity is reduced toward the distal end.Moreover, an area including the fourth area 434 x forms a rigidityuniform portion 402 x in which the rigidity is uniform in the axialdirection. If the above constitution is adopted, when inserting thecatheter assembly 10 x into a blood vessel, the surgeon can more safelyinsert it into the blood vessel while securing sufficient pushabilityand sufficiently transmitting torque to the distal side.

Examples of constituent materials of the first area 431 x, the secondarea 432 x, the third area 433 x, and the fourth area 434 x includevarious thermoplastic elastomers based on styrene, polyolefin,polyurethane, polyester, polyamide, polybutadiene, transpolyisoprene,fluororubber, chlorinated polyethylene, and the like. For example, onekind of these may be used singly, or a combination of two or more kindsthereof (a polymer alloy, a polymer blend, a laminate, and the like) maybe used.

It is preferable for the inner layer 42 x to be made of a material orprovided with properties which, when at least a portion of the outercatheter lumen 41 x comes into contact with a medical instrument, thecontact is a relatively small frictional force, when the medicalinstrument such as a catheter for treatment or a guide wire is insertedinto the outer catheter lumen 41 x. If such a material is used, themedical instrument inserted into the outer catheter body 40 x can bemoved in the axial direction with a lower sliding resistance, wherebythe operability is improved. The entire inner layer 42 x may be made ofa low-friction material. Examples of the low-friction material includefluororesin materials such as polytetrafluoroethylene (PTFE).

The surgeon inserts the catheter assembly 10 x into the body whilechecking its position under radiography. Accordingly, it is preferablefor the constituent material of the outer catheter body 40 x to containa radiopaque material (X-ray contrast agent). Examples of the radiopaquematerial which can be used include barium sulfate, bismuth oxide andtungsten. The radiopaque material may be present throughout the fulllength of the outer catheter body 40 x or may be present in a portion ofthe outer catheter body 40 x.

The reinforcing layer 44 x is for reinforcing the outer catheter body 40x, and contains a reinforcing material consisting of or including pluralreinforcing wires 441 x. The gaps between the plural reinforcing wires441 x in the reinforcing layer 44 x are filled with the material of theouter layer 43 x or the inner layer 42 x. Examples of the reinforcingmaterial include the reinforcing wire 441 x that is in the form of ahelix or a net. The reinforcing wire 441 x is made of metals such asstainless steel and NiTi. Specific examples of the wire-like materialinclude a flat plate-shaped material that is obtained by squashing astainless steel wire to form a flat-shaped like wire such that thethickness of the outer catheter 20 x in the radial direction thereofbecomes small. Examples of the reinforcing material also include a helixformed of plural strands (about 8 to 32 strands) of the wire, a material(braid) obtained by braiding the wires, and the like. The number ofstrands of the reinforcing wire 441 x is preferably a multiple of 8,since the catheter is reinforced well with excellent balance in the formof a tube in this manner. The reinforcing wire 441 x is not limited tothe aforementioned flat plate-shaped material, and may be, for example,a round wire or an oval wire. Moreover, a strand of the reinforcing wire441 x may be a bundle of two or more strands of wires.

Since the catheter has the reinforcing layer 44 x, the catheter exhibitssufficient rigidity and strength, without increasing the thickness ofthe wall of the outer catheter body 40 x. The outer catheter body 40 xcan thus maintain a relatively large inner diameter. As a result, amedical instrument that has a relatively large outer diameter can beinserted into the catheter, and the outer catheter 20 x that hasexcellent pushability and torque-transmitting properties and is noteasily kinked or crushed is obtained.

The soft tip 45 x is more flexible than the tubular body 80 x havingthree-layer structure consisting of the inner layer 42 x, thereinforcing layer 44 x, and the outer layer 43 x. Accordingly, when thecatheter assembly 10 x that is in an assembled state is inserted intothe body, it is possible to minimize the damage of a blood vessel causedby the distal end of the outer catheter body 40 x.

Examples of the constituent material of the soft tip 45 x includevarious rubber materials such as natural rubber, isoprene rubber,butadiene rubber, chloroprene rubber, silicone rubber, fluororubber, andstyrene-butadiene rubber, and various thermoplastic elastomers based onstyrene, polyolefin, polyurethane, polyester, polyamide, polybutadiene,transpolyisoprene, fluororubber, chlorinated polyethylene, and the like.

The outer diameter of the outer catheter body 40 x is preferably from1.35 mm to 3 mm. If the outer diameter is too large, operability at thetime when the outer catheter body 40 x is inserted into and moved insidean artery may deteriorate, and the strain that the patient suffers frommay increase.

The inner diameter of the outer catheter body 40 x is preferably from1.2 mm to 2.85 mm. If the inner diameter is too small, it is notpreferable since the outer diameter of a catheter for treatment that canbe inserted into the outer catheter body 40 x also needs to be reducedaccordingly, and a choice of medical instruments to be inserted and usedis restricted.

The length of the outer catheter body 40 x can be appropriately setaccording to the use of the outer catheter 20 x, and is, for example,500 mm to 2,500 mm.

The outer catheter hub 50 x is fixed to the proximal end of the outercatheter body 40 x. As shown in FIGS. 13 and 14, the outer catheter hub50 x is configured to include a hollow external catheter body portion 51x, plural (two in the present embodiment) outer catheter blade portions52 x that protrude radially outwardly from the outer lateral surface ofthe external catheter body portion 51 x, and a helical bump orenlargement 53 x that is formed on the outer lateral surface of theproximal portion of the external catheter body portion 51 x. In theexternal catheter body portion 51 x, an outer catheter hub lumen 54 xthat comes into contact with the outer catheter lumen 41 x and an outercatheter hub opening portion 55 x that is open at the proximal end ofthe outer catheter hub lumen 54 x are formed. The helical bump 53 x canbe screwed with a helical groove 99 x that is formed in a screwingportion 93 x which is disposed in the inner catheter hub 90 x and willbe described later. A cylindrical portion 97 x which is formed at thedistal end of the inner catheter hub 90 x can be inserted into the outercatheter hub opening portion 55 x. The helical bump 53 x and thescrewing portion 93 x constitute a lock mechanism for maintaining thestate where the outer catheter hub 50 x is connected to the innercatheter hub 90 x.

The outer catheter hub lumen 54 x includes a tapered portion 56 x whoseinner diameter is reduced toward the distal end from the outer catheterhub opening portion 55 x. The tapered portion 56 x is a female luertaper configured to be fitted to or with a male luer taper formed on theouter surface of the cylindrical portion 97 x of the inner catheter hub90 x. When a medical instrument such as a balloon catheter is insertedfrom the outer catheter hub opening portion 55 x, the tapered portion 56x guides the medical instrument into the outer catheter lumen 41 x byusing the inner surface of which the inner diameter is reduced towardthe distal end.

Examples of the constituent material of the outer catheter hub 50 xinclude various thermoplastic elastomers based on styrene, polyolefin,polyurethane, polyester, polyamide, polybutadiene, transpolyisoprene,fluororubber, chlorinated polyethylene, and the like. For example, onekind of these may be used alone, or a combination of two or more kindsthereof (a polymer alloy, a polymer blend, a laminate, and the like) maybe used.

In the assembled state, the inner catheter 30 x is inserted into theouter catheter hub 50 x from the proximal side. However, after the innercatheter 30 x is pulled out, for example, an elongated device/substance(linear device/substance) such as a guide wire, catheters (for example,a balloon catheter for PTCA), an endoscope, an ultrasonic probe, or atemperature sensor can be inserted into the outer catheter hub 50 x orpulled out of the outer catheter hub 50 x. Alternatively, variousliquids such as a contrast agent (X-ray contrast agent), a drugsolution, and physiological saline can be injected into the outercatheter hub 50 x.

The anti-kink protector 60 x is mounted on the catheter such that itcovers a portion where the outer catheter body 40 x is connected to theouter catheter hub 50 x. The anti-kink protector 60 x inhibits the outercatheter 20 x from kinking at the position at which the anti-kinkprotector 60 x is located.

Next, the inner catheter 30 x will be described. As shown in FIGS. 13and 14, the tubular body 80 x disposed in the inner catheter 30 x has atubular body proximal portion 81 x possessing an outer diameter that isconstant in the axial direction, and a tubular body distal portion 82 xpossessing an outer diameter that reduced such that the portion 82 x istapered toward the distal end in the axial direction. The axial centralportion of the tubular body 80 x includes an inner catheter lumen 83 xthat penetrates the tubular body 80 x from the distal end to theproximal end. The outer diameter of the tubular body proximal portion 81x is approximately the same as the inner diameter of the outer catheterbody 40 x. As long as the tubular body 80 x can be inserted into andpulled out of the outer catheter body 40 x, the outer diameter of thetubular body proximal portion 81 x need not be the same as the innerdiameter of the outer catheter body 40 x. When the tubular body proximalportion 81 x is disposed inside the outer catheter body 40 x, the outersurface of the tubular body proximal portion 81 x comes into contactwith the inner surface of the outer catheter body 40 x without aclearance, or is positioned adjacent the inner surface with a smallclearance.

The inner diameter of the tubular body 80 x may be set to beapproximately the same as the outer diameter of the guide wire to beused. As long as the guide wire can be inserted into or pulled out ofthe tubular body 80 x, the inner diameter of the tubular body 80 x neednot be the same as the outer diameter of the guide wire. For example,when inserting the guide wire into the catheter assembly prior to theinsertion of the guide wire into the body lumen, the surgeon inserts theguide wire toward the distal end of the tubular body 80 x from an innercatheter hub opening portion 95 x in some cases. In this case, regardingthe inner diameter of the tubular body 80 x, it is preferable for theinner diameter of the proximal opening of the tubular body 80 x to belarger than the inner diameter of the distal opening of the tubular body80 x. Moreover, in the distal portion of the tubular body 80 x, when theguide wire is disposed inside the inner catheter lumen 83 x, the outersurface of the guide wire comes into contact with the inner surface ofthe tubular body 80 x without a clearance or is positioned adjacent theinner surface with a small clearance.

The length of the tubular body 80 x is not particularly limited, and is,for example, 200 mm to 600 mm.

In the assembled state, the length L1 between the distal end of thetubular body 80 x and the distal end of the outer catheter body 40 x inthe axial direction is smaller than the length L2 between the distal endof the outer catheter body 40 x and the proximal end of the tubular body80 x in the axial direction as shown in FIG. 15. Moreover, the length L2is sufficient for the tubular body 80 x to be accommodated inside theouter catheter 20 x. The length L1 is not particularly limited and is,for example, 30 mm to 50 mm.

In addition, in the assembled state, the proximal end of the tubularbody 80 x is positioned in a portion closer to the proximal side than tothe distal end of the rigidity uniform portion 402 x of the outercatheter body 40 x. That is, the proximal end (proximal-most end) of thetubular body 80 x is located on the proximal side of the distal end(distal-most end) of the rigidity uniform portion 402 x. Furthermore, inthe assembled state, the tubular body distal portion 82 x is positionedin a portion closer to the distal side than to the distal end of theouter catheter body 40 x. That is, the tapered portion 82 x is located(entirely in the illustrated embodiment) on the distal side of thedistal end (distal-most end) of the outer catheter body 40 x.

Examples of the constituent material of the tubular body 80 x includevarious thermoplastic elastomers based on styrene, polyolefin,polyurethane, polyester, polyamide, polybutadiene, transpolyisoprene,fluororubber, chlorinated polyethylene, and the like. For example, onekind of these may be used singly, or a combination of two or more kindsthereof (a polymer alloy, a polymer blend, a laminate, and the like) maybe used.

As shown in FIGS. 13 and 14, the inner catheter hub 90 x has a hollowinner catheter body portion 91 x, plural (two in the present embodiment)inner catheter blade portions 92 x that protrude outwardly from theouter lateral surface of the inner catheter body portion 91 x, and thescrewing portion 93 x that is rotatably disposed on the outer lateralsurface of the inner catheter body portion 91 x.

The inner catheter body portion 91 x includes an inner catheter hublumen 94 x that penetrates the inner catheter body portion 91 x from theproximal end to the distal end. The inner catheter hub lumen 94 x opensto the inner catheter hub opening portion 95 x at the proximal end ofthe inner catheter body portion 91 x. It is preferable for the innerdiameter of the inner catheter hub lumen 94 x to be larger than theouter diameter of a guide wire to be used. If the above configuration isadopted, a contact area between the outer surface of the guide wire andthe inner circumferential surface of the inner catheter hub lumen isreduced, and accordingly, the surgeon can rather easily operate theguide wire at his or her side. Moreover, when inserting the catheterassembly into the body lumen, the surgeon can rather easily insert theguide wire from the distal portion of the tubular body 80 x to the innercatheter hub opening portion 95 x. As long as the guide wire can beinserted into and pulled out of the inner catheter hub lumen 94 x, theinner diameter of the inner catheter hub lumen 94 x may be approximatelythe same as the outer diameter of the guide wire to be used.

The outer surface of the inner catheter body portion 91 x includes acircumferentially extending groove portion 96 x rotatably fitted to thescrewing portion 93 x.

The cylindrical portion 97 x that is insertable into the outer catheterhub opening portion 55 x of the outer catheter hub 50 x is located atthe distal end of the inner catheter body portion 91 x. The outersurface of the cylindrical portion 97 x constitutes a male luer taper inwhich the outer diameter is reduced toward the distal end. When thecylindrical portion 97 x is inserted into the outer catheter hub openingportion 55 x, the outer surface (male luer taper) of the cylindricalportion 97 x comes into close contact with the tapered portion 56 x(female luer taper) of the outer catheter hub lumen 54 x. As a result,it is possible to communicate the outer catheter hub lumen 54 x with theinner catheter lumen 83 x while securing a liquid-tight state.

The screwing portion 93 x is in the form of a tube. The inner surface ofthe proximal end of the screwing portion 93 x includes acircumferentially extending bump for engagement 98 x (an inwardlyprojecting engaging portion) which rotatably engages the groove portion96 x on the inner catheter body portion 91 x. Moreover, the innersurface of the screwing portion 93 x includes the helical groove 99 xconfigured to be screw-engaged with the helical bump or enlargement 53 xof the outer catheter hub 50 x. When the cylindrical portion 97 x isinserted into the outer catheter hub opening portion 55 x, and thescrewing portion 93 x is rotated, the helical bump or enlargement 53 xscrew engages the helical groove 99 x, and the cylindrical portion 97 xis pushed into the outer catheter hub lumen 54 x toward the distal end.As a result, the outer surface of the cylindrical portion 97 x comesinto close contact with the tapered portion 56 x of the outer catheterhub lumen 54 x, and a state where the outer catheter hub 50 x isconnected to the inner catheter hub 90 x can be maintained.

Examples of the material which can be used for the inner catheter hub 90x include various thermoplastic elastomers based on styrene, polyolefin,polyurethane, polyester, polyamide, polybutadiene, transpolyisoprene,fluororubber, chlorinated polyethylene, and the like. For example, onekind of these may be used singly, or a combination of two or more kindsthereof (a polymer alloy, a polymer blend, a laminate, and the like) maybe used.

As shown in FIGS. 13 and 14, the shaft 70 x is a flexible member thatextends in the form of a straight line. The distal portion of the shaft70 x is fixed to the tubular body 80 x at a position that deviates fromthe inner catheter lumen 83 x of the proximal surface of the tubularbody 80 x outside the radial direction. That is, the shaft 70 x and theinner catheter lumen 83 x are not coaxial. The proximal portion of theshaft 70 x is fixed to the cylindrical portion 97 x of the innercatheter hub 90 x at a position that deviates from the inner catheterhub lumen 94 x of the distal surface of the cylindrical portion 97 x ofthe inner catheter hub 90 x outside the radial direction. That is, theshaft 70 x and the inner catheter hub lumen 94 x of the inner catheterhub 90 x are not coaxial. The shaft 70 x flexibly bends while havingappropriate rigidity, such that when the inner catheter hub 90 x isoperated, the tubular body 80 x moves in the axial directionsimultaneously with the inner catheter hub 90 x, and the tubular body 80x to which a force is applied from a body tissue when it is insertedinto the body, is not pushed back to the inside of the outer catheterbody 40 x.

It is preferable to appropriately set the length of the shaft 70 x inthe axial direction according to the length of the outer catheter body40 x, such that in the assembled state, the distal end of the tubularbody 80 x is positioned in a portion closer to the distal side than tothe distal end of the outer catheter body 40 x, and the proximal end ofthe tubular body 80 x is positioned in a portion closer to the proximalside than to the proximal end of the outer catheter body 40 x. That is,in the assembled state such as shown in FIG. 15, the distal end(distal-most end) of the tubular body 80 x is located on the distal sideof the distal end (distal-most end) of the outer catheter body 40 x(soft tip 45 x). And, in the assembled state, the proximal(proximal-most) end of the tubular body 80 x is located on the distalside of the proximal (proximal-most) end of the outer catheter body 40 x(taking into account that the outer catheter body 40 x does not includethe outer catheter hub 50 x).

The outer diameter of the shaft 70 x is preferably from 0.3 mm to 1.5mm, but is not limited to this dimensional range. Moreover, the outerdiameter of the shaft 70 x is set to be smaller than the inner diameterof the outer catheter body. If the outer diameter of the shaft 70 x istoo large, the movement of the guide wire inside the outer catheterlumen 41 x is hindered in the assembled state. If the outer diameter ofthe shaft 70 x is too small, it is difficult to move the tubular body 80x simultaneously with the inner catheter hub 90 x.

The material forming the shaft 70 x is not particularly limited as longas the rigidity is obtained as required. Examples of materials includemetals such as stainless steel and NiTi, various thermoplasticelastomers based on styrene, polyolefin, polyurethane, polyester,polyamide, polybutadiene, transpolyisoprene, fluororubber, chlorinatedpolyethylene, and the like, thermosetting resins such as unsaturatedpolyester, a urea resin, a melamine resin, a silicon resin, a phenolresin, and an epoxy resin, and the like. For example, one kind of thesemay be used singly, or a combination of two or more kinds thereof (apolymer alloy, a polymer blend, a laminate, and the like) may be used.Moreover, the shaft 70 x may be constituted with plural materials.

In the assembled state, as shown in FIG. 15, the distal end of thetubular body 80 x is disposed in a portion closer to the distal sidethan to the distal end of the outer catheter body 40 x, and the proximalend of the tubular body 80 x is disposed in a portion closer to theproximal side than to the distal end of the outer catheter body 40 x.That is, as explained above, in the assembled state, the distal end(distal-most end) of the tubular body 80 x is located on the distal sideof the distal end (distal-most end) of the outer catheter body 40 x, andthe proximal (proximal-most) end of the tubular body 80 x is located onthe distal side of the proximal (proximal-most) end of the outercatheter body 40 x. Accordingly, when a guide wire 120 x is insertedinto the inner catheter lumen 83 x, the tubular body 80 x is positionedin a gap between the outer surface of the guide wire 120 x and the innersurface of the outer catheter body 40 x (see FIG. 17).

Moreover, in the assembled state, in a cross section which is orthogonalto the axis of the outer catheter body 40 x in the distal end of theouter catheter body 40 x, the thickness of the tubular body 80 x in theradial direction of the tubular body 80 x is larger than the thicknessof the outer catheter body 40 x in the radial direction of the outercatheter body 40 x. Accordingly, the surgeon can prevent the distal endof the outer catheter body 40 x from protruding from the outer surfaceof the tubular body 80 x outside the radial direction as much aspossible, while bringing the distal end of the outer catheter body 40 xinto contact with the outer surface of the tubular body 80 x.

Set forth next is a description of a manner of using the catheterassembly 10 x according to the present embodiment. In the followingdescription, for example, a method will be explained in which thesurgeon uses the outer catheter 20 x as a guiding catheter andintroduces a balloon catheter 100 x into a blood vessel through theguiding catheter so as to treat a stenosed portion in the blood vessel.The balloon catheter 100 x is a rapid exchange type. As shown in FIGS.20 and 22, a guide wire lumen 102 x into which the guide wire 120 x isinserted is formed only in the distal portion of the balloon catheter100 x in which a balloon 101 x is disposed. In the balloon catheter 100x, when a fluid for dilation is supplied into the balloon 101 x of thedistal portion from a balloon catheter hub 103 x through a lumen fordilation formed in a balloon catheter shaft 104 x, the balloon 101 x isdilated outside the radial direction by the force of fluid.

First, before the catheter assembly 10 x is introduced into a bloodvessel, the outer catheter 20 x and the inner catheter 30 x areassembled as shown in FIGS. 12, 14, and 15, thereby constituting thecatheter assembly 10 x (supply step). At the time of assembly, the innercatheter 30 x is inserted into the outer catheter hub opening portion 55x from the tubular body 80 x, and is pushed forward until thecylindrical portion 97 x is inserted into or positioned in the outercatheter hub opening portion 55 x. When the screwing portion 93 x isrotated after the cylindrical portion 97 x is inserted into the outercatheter hub opening portion 55 x, the helical bump or enlargement 53 xis screwed into the helical groove 99 x as shown in FIG. 14. As aresult, the cylindrical portion 97 x is pushed into the outer catheterhub lumen 54 x toward the distal end, and the outer surface of thecylindrical portion 97 x comes into close contact with the taperedportion 56 x of the outer catheter hub lumen 54 x. Accordingly, theouter catheter hub lumen 54 x communicates with the inner catheter lumen83 x in a liquid-tight state, and this state can be reliably maintained.Therefore, the outer catheter 20 x and the inner catheter 30 x can beintegrally operated when the catheter assembly 10 x is inserted into ablood vessel. For this reason, the catheter assembly is rather easilyoperated, and the outer catheter 20 x and the inner catheter 30 x areinhibited from being accidentally disassembled, whereby the safety isimproved.

Next, as shown in FIG. 16, by a known method such as Seldingertechnique, the surgeon makes a puncture in the radial artery and insertsa mini-guide wire into the artery. Thereafter, the surgeon inserts acatheter introducer 110 x, which is obtained by inserting a dilator intothe lumen of sheath 111 x, into the punctured portion of the radialartery along the mini-guide wire. After moving the distal end of thecatheter introducer 110 x to the central side by a predetermineddistance, the surgeon withdraws the mini-guide wire and the dilator fromthe catheter introducer 110 x, and leaves the sheath 111 x inside theradial artery. In this manner, the surgeon can secure an introductionportion for introducing the catheter assembly 10 x into the radialartery. In the following description, a case will be explained in detailin which the surgeon introduces the catheter assembly 10 x from theradial artery and treats a stenosed portion present in a blood vesselsuch as the femoral artery in a lower limb. However, the specific use ofthe catheter disclosed here is not particularly limited. For example,the surgeon may introduce the catheter assembly 10 x from the brachialartery, the femoral artery, or the like. Moreover, the position of thesite to be treated, such as a stenosed portion, is not particularlylimited.

After securing the introduction portion in the radial artery of an arm,the surgeon inserts the guide wire 120 x into the catheter assembly 10 x(guide wire insertion step). Specifically, the surgeon inserts the guidewire 120 x into the inner catheter lumen 83 x, the outer catheter lumen41 x, the outer catheter hub lumen 54 x, and the inner catheter hublumen 94 x that constitute the catheter assembly 10 x. Subsequently, thesurgeon inserts the catheter assembly 10 x, in which the guide wire hasbeen inserted, from the distal opening of the sheath 111 x. The surgeonthen introduces the distal end of the catheter assembly 10 x into theradial artery along the guide wire 120 x (introduction step). The guidewire insertion step may be performed before the introduction portion issecured in the radial artery of an arm.

In the delivery step, as shown in FIG. 17, led by the guide wire 120 x,the catheter assembly 10 x in the assembled state is slowly pushedtoward the stenosed portion (target site). For example, when thecatheter assembly 10 x is introduced to the femoral artery from theradial artery as in the first embodiment, the surgeon checks theposition of the distal portion of the guide wire 120 x by radiographyand the like, and while doing this, the surgeon introduces the catheterassembly 10 x into the femoral artery as the target site through theradial artery, the brachial artery, the subclavian artery, thebrachiocephalic artery, the thoracic aorta, the abdominal aorta, thecommon iliac artery, and the external iliac artery. At this time, in thecatheter assembly 10 x, the tubular body 80 x is disposed inside theouter catheter body 40 x. The tubular body 80 x is positioned in a gapbetween the outer surface of the guide wire 120 x to be inserted intothe inner catheter lumen 83 x and the inner surface of the outercatheter body 40 x, and the outer diameter of the tubular body 80 x issmaller in the distal portion of the tubular body 80 x than in theproximal portion of the tubular body 80 x. Accordingly, with thecatheter assembly 10 x, the surgeon can reduce a step difference formedbetween the outer surface of the outer catheter body 40 x and the outersurface of the guide wire 120 x, while bringing the distal end of theouter catheter body 40 x into contact with the outer surface of thetubular body 80 x. As a result, the surgeon can suppress the damage of ablood vessel as much as possible, and inhibit rolling of the outercatheter body 40 x that is caused when the distal end of the outercatheter body 40 x receives resistance from the blood vessel. Moreover,since the distal end (distal-most end) of the tubular body distalportion 82 x whose outer diameter is reduced toward the distal end ofthe tubular body distal portion 82 x is positioned distally of thedistal end (distal-most end) of the outer catheter body 40 x, thetubular body distal portion 82 x smoothly comes into contact with theblood vessel, and accordingly, damage of the blood vessel can besuppressed as much as possible.

In the assembled state, within the cross section of the distal end ofthe outer catheter body 40 x that is orthogonal to the axis of the outercatheter body 40 x, the thickness of the tubular body 80 x in the radialdirection is larger than the thickness of the outer catheter body 40 xin the radial direction. Therefore, with the catheter assembly 10 x, thesurgeon can reduce a step difference formed between the outer surface ofthe outer catheter body 40 x and the outer surface of the tubular body80 x, and further suppress the damage of the blood vessel.

Moreover, in the assembled state, the length L1 between the distal endof the tubular body 80 x and the distal end of the outer catheter body40 x in the axial direction is smaller than the length L2 between thedistal end of the outer catheter body 40 x and the proximal end of thetubular body 80 x in the axial direction. Accordingly, the length L2 issufficient for the tubular body 80 x to be accommodated inside the outercatheter 20 x, whereby the tubular body 80 x can be inhibited fromkinking in the distal area of the outer catheter body 40 x. As a result,when inserting the catheter assembly 10 x into a blood vessel, thesurgeon can more safely inserts the catheter assembly into the bloodvessel, while securing sufficient pushability or sufficientlytransmitting torque to the distal side.

In the assembled state, the proximal end of the tubular body 80 x ispositioned proximally of the distal end (distal-most end) of therigidity uniform portion 402 x of the outer catheter body 40 x.Accordingly, the proximal end of the tubular body 80 x is not positionedin the middle of the rigidity transition portion 401 x in which therigidity is reduced toward the distal end, and the transition ofrigidity of the outer catheter body 40 x can be excellently maintained.As a result, when inserting the catheter assembly 10 x into a bloodvessel, the surgeon can more safely insert the catheter assembly intothe blood vessel, while securing sufficient pushability or sufficientlytransmitting torque to the distal side.

After the distal end of the catheter assembly 10 x reaches the targetsite, the surgeon rotates the screwing portion 93 x to disconnect thehelical groove 99 x from the helical bump or enlargement 53 x. Moreover,as shown in FIGS. 18 and 19, the surgeon pulls the inner catheter 30 xout of the outer catheter 20 x while leaving the outer catheter 20 x andthe guide wire 120 x inside the blood vessel. At this time, the tubularbody 80 x disposed at the distal side of the shaft 70 x of the innercatheter 30 x includes an inner catheter lumen 83 x, which opens to theoutside in the distal portion and the proximal portion of the tubularbody 80 x and enables the guide wire 120 x to be inserted in the innercatheter lumen 83 x. Furthermore, at the distal side of the tubular body80 x, the guide wire 120 x is positioned not in the inside of but in theoutside of the inner catheter 30 x. Therefore, when the inner catheterhub 90 x moves proximally to a position on the proximal side of theproximal end (proximal-most end) of the guide wire 120 x, the guide wire120 x is pulled out of the inner catheter hub lumen 94 x toward thedistal side. As a result, except for the inner catheter lumen 83 x ofthe tubular body 80 x, the guide wire 120 x is positioned outside theinner catheter 30 x. That is, the guide wire 120 x is positionedexterior of the shaft 70 x. Accordingly, even though the guide wire 120x is not excessively lengthened, the inner catheter 30 x can bewithdrawn along the guide wire 120 x (inner catheter withdrawal step).Specifically, at the time of withdrawal of the inner catheter 30 x, thecatheter assembly 10 x maintains a state in which the guide wire 120 xis exposed without being hidden in the inner catheter 30 x at thesurgeon's side where the assembly is operated. Therefore, a high degreeof operability of the guide wire 120 x is obtained.

After the inner catheter 30 x is completely pulled out of the outercatheter 20 x, by using the helical bump or enlargement 53 x of theouter catheter hub 50 x, the surgeon connects a general Y-connector 130x, which has a connection portion 133 x having a structure similar tothe screwing portion 93 x and the cylindrical portion 97 x (see FIG. 14)of the aforementioned inner catheter hub 90 x, to the outer catheter hub50 x as shown in FIG. 20. The Y-connector 130 x has a first port 131 xthat includes a hemostasis valve and a second port 132 x that is forinjecting a contrast agent and the like. By connecting the connectionportion 133 x to the outer catheter hub 50 x, communication between theouter catheter hub lumen 54 x and the first port 131 x as well as thesecond port 132 x is established. When the Y-connector 130 x isconnected to the outer catheter hub 50 x, the guide wire 120 x, which isexposed to the proximal side from the outer catheter hub opening portion55 x, is brought out of the first port 131 x through the hemostasisvalve. The second port 132 x can be connected to a contrastagent-containing syringe or the like. When pushed out of the syringe orthe like, the contrast agent can pass through the outer catheter hublumen 54 x and the outer catheter lumen 41 x and can be discharged fromthe distal end of the outer catheter body 40 x. The liquid accommodatedin the syringe or the like is not limited to the contrast agent and maybe a drug or physiological saline.

Next, the surgeon inserts the proximal end of the guide wire 120 x fromthe distal side of the guide wire lumen 102 x of the balloon catheter100 x, and then inserts the balloon catheter 100 x into the first port131 x along the guide wire 120 x as shown in FIG. 21. Thereafter, thesurgeon moves the balloon catheter 100 x in the outer catheter lumen 41x toward the distal end and causes the balloon 101 x to protrude to thedistal side from the outer catheter body 40 x. Subsequently, the surgeoncauses the balloon catheter 100 x to advance, until the surgeon confirmsa state where the balloon 101 x has been delivered to a positioncorresponding to the stenosed portion as a treatment target in the bloodvessel under radiography (device advance step). Next, the surgeonconnects a syringe or the like that accommodates a fluid for dilation tothe balloon catheter hub 103 x, supplies the fluid for dilation to theballoon 101 x through the lumen for dilation, thereby dilating theballoon 101 x as shown in FIG. 22. In this manner, the surgeon canprovide treatment in which the balloon 101 x is dilated so as to expand,for example, a stenosed portion (target site) as a treatment target inthe blood vessel by using the balloon 101 x (treatment step).

Thereafter, the fluid for dilation is discharged out of the balloon 101x through the lumen for dilation, whereby the balloon 101 x contracts.The surgeon then withdraws the balloon catheter 100 x and the guide wire120 x from the outer catheter 20 x.

The treatment performed through the outer catheter 20 x is not limitedto the treatment performed using the balloon catheter 100 x. Forexample, a stent may be disposed on the outer surface of the balloon 101x. If the stent is disposed on the outer surface of the balloon 101 x,when the balloon 101 x is dilated, the stent expands while undergoingplastic deformation. When the balloon 101 x is contracted, the stenthaving undergone plastic deformation remains on the inner wall surfaceof the blood vessel without being contracted, and the blood vessel canbe maintained excellently in the state of being expanded by the stent.Moreover, through the outer catheter 20 x, insertion or withdrawal of anelongated device/substance such as a catheter other than the ballooncatheter 100 x, an endoscope, an ultrasonic probe, or a temperaturesensor can be performed, or alternatively, injection of various liquidssuch as a contrast agent (X-ray contrast agent), a drug solution, andphysiological saline can be performed. Thereafter, the outer catheter 20x is pulled out of the sheath 111 x, the sheath 111 x is pulled out ofthe radial artery, and the blood from the portion punctured by thesheath 111 x is stanched to complete the procedure.

As described above, particularly when a blood vessel of a lower limb,such as the femoral artery, is treated from a blood vessel of an arm,such as the radial artery, by a TRI technique, the surgeon has to use along catheter assembly and guide wire since a distance between theinsertion site of the catheter assembly and the treatment site is long.Consequently, when the surgeon uses an over-the-wire type innercatheter, it takes a long time for the surgeon to withdraw the innercatheter. The inner catheter 30 x of the catheter assembly 10 xdisclosed here is a rapid exchange-type catheter. Accordingly, it iseasy for the surgeon to withdraw the inner catheter 30 x while leavingthe outer catheter 20 x and the guide wire inside the body lumen.Therefore, the catheter assembly 10 x disclosed here by way of exampleis suitable for the case where a blood vessel of a lower limb, such asthe femoral artery, is treated from a blood vessel of an arm, such asthe radial artery.

The intervention device (catheter assembly 10 x) used in the treatmentmethod of the third embodiment is not limited to the form of thecatheter assembly 10 x. For example, the catheter assembly 10 x may bein the form of a seventh modified example described below. A catheterassembly 140 x according to the seventh modification example differsfrom the catheter assembly used in the treatment method of the thirdembodiment, only in terms of the construction of an inner catheter 150x. Moreover, the portions of the catheter assembly 10 x used in thetreatment method according to the third embodiment that are similar tothose in the embodiments described above are identified by a commonreference numeral and a detailed description of such aspects is notrepeated.

As shown in FIGS. 23 and 24, the tubular body 160 x of the innercatheter 150 x of the seventh modified example includes, in addition tothe inner catheter lumen 83 x into which a guide wire is inserted, asecond inner catheter lumen 161 x that penetrates the tubular body 160 xfrom the distal end to the proximal end. Moreover, the shaft 70 x isfixed to a position different from the portion in which the innercatheter lumen 83 x and the second inner catheter lumen 161 x of thetubular body 160 x are formed. The second inner catheter lumen 161 xserves as a flow path through which a liquid such as a contrast agent orphysiological saline flows. It is preferable for the inner diameter ofthe inner catheter lumen 83 x to be larger than the inner diameter ofthe second inner catheter lumen 161 x. If the above configuration isadopted, when a guide wire is inserted into the inner catheter lumen 83x of the tubular body 160 x, since the inner diameter of the secondinner catheter lumen 161 x is smaller than the size of the innercatheter lumen 83 x which has an inner diameter approximately the sameas the outer diameter of the guide wire, the risk that the surgeon mayaccidentally insert the guide wire into the second inner catheter lumen161 x is reduced. Moreover, in the assembled state in which an innercatheter hub 170 x is connected to the outer catheter hub 50 x, it ispreferable for the tubular body 160 x to have a tapered portion of whichthe outer diameter increases toward the proximal side from the distalend of the tubular body 160 x, with the tapered portion located(entirely in the illustrated embodiment) on the distal side of thedistal end (distal-most end) of the outer catheter 20 x. At this time,it is more preferable for the tubular body 160 x to be configured sothat the inner catheter lumen 83 x penetrates the tubular body 160 xfrom the distal end of the tubular body 160 x to the proximal end of thetubular body 160 x, and the second inner catheter lumen 161 x penetratesthe tubular body 160 x from the tapered portion of the tubular body 160x to the proximal end of the tubular body 160 x. A distal opening of theinner catheter lumen 83 x is positioned in a portion closer to a distalopening of the second inner catheter lumen 161 x than to the distalside. If the above constitution is adopted, when the guide wire isinserted into the inner catheter lumen 83 x of the tubular body 160 x,the risk that the surgeon may accidentally insert the guide wire intothe second inner catheter lumen 161 x can be reduced. In addition, inthe catheter assembly 140 x, the inner catheter lumen 83 x into whichthe guide wire is inserted is formed in a portion near the center of thetubular body 160 x. Accordingly, operability of the guide wire can beimproved.

As shown in FIG. 25, in the inner catheter hub 170 x of the innercatheter 150 x, a port 171 x that is for injecting a liquid such as acontrast agent or physiological saline is formed. Moreover, the port 171x includes a second inner catheter hub lumen 172 x that extends to thedistal surface of the cylindrical portion 97 x of the inner catheter 150x. Accordingly, in the inner catheter hub 170 x, the inner catheter hublumen 94 x into which the guide wire is inserted and the second innercatheter hub lumen 172 x are formed. The second inner catheter hub lumen172 x can function as a flow path through which a liquid such as acontrast agent or physiological saline can flow.

Next, the action of the catheter assembly 140 x according to the seventhmodified example will be described.

In the catheter assembly 140 x according to the seventh modifiedexample, the second inner catheter lumen 161 x is formed in the tubularbody 160 x of the inner catheter 150 x as shown in FIGS. 23 and 24, andthe second inner catheter hub lumen 172 x is formed in the innercatheter hub 170 x as shown in FIG. 25. Accordingly, in a state wherethe guide wire is inserted into the inner catheter lumen 83 x and theinner catheter hub lumen 94 x, when the port 171 x is connected to asyringe or the like that accommodates a liquid such as a contrast agent,physiological saline, or a drug, and the liquid is injected into thecatheter, the liquid, which has been injected into the outer catheterbody 40 x through the second inner catheter hub lumen 172 x, flows tothe distal end through the outer catheter lumen 41 x and then isdischarged to the distal side (end) of the catheter assembly 140 xthrough the second inner catheter lumen 161 x of the tubular body 160 x.At this time, the liquid is delivered to the distal end by using theouter catheter lumen 41 x which is positioned at the outside of theinner catheter 150 x and has a relatively large inner diameter until theliquid reaches the second inner catheter lumen 161 x. Therefore,pressure loss is reduced, and the liquid can be easily pushed out by asmall force. Accordingly, the catheter assembly 140 x is particularlyeffective for injecting a liquid with high viscosity, such as a contrastagent.

A catheter assembly 180 x according to an eighth modified example usedin the treatment method of the third embodiment differs from thecatheter assembly 10 x used in the treatment method of the thirdembodiment, only in terms of the configuration or construction of aninner catheter 190 x. A catheter assembly 180 x according to the eighthmodified example differs from the catheter assembly used in thetreatment method of the third embodiment, only in terms of theconstruction of an inner catheter 150 x. The portions of the catheterassembly 10 x, 140 x used in the treatment method according to the thirdembodiment that are similar to those in the embodiments described aboveare identified by a common reference numeral and a detailed descriptionof such aspects is not repeated.

As shown in FIGS. 26 and 27, in a tubular body 200 x of the innercatheter 190 x in the eighth modified example, in addition to the innercatheter lumen 83 x into which the guide wire 120 x is inserted, asecond inner catheter lumen 201 x that penetrates (passes through) thetubular body 200 x from the distal end of the tubular body 200 x to thedistal end thereof is formed.

In an inner catheter hub 210 x of the inner catheter 190 x, a port 211 xfor injecting a liquid such as a contrast agent or physiological salineis formed as shown in FIG. 28. Moreover, in the port 211 x, a secondinner catheter hub lumen 212 x that extends to the distal surface of thecylindrical portion 97 x of the inner catheter 190 x is formed.

A shaft 220 x of the inner catheter 190 x is a tubular body in which ashaft lumen 221 x that penetrates the shaft in the axial direction isformed. The distal portion of the shaft 220 x is fixed to the tubularbody 200 x as shown in FIGS. 26 and 27 such that the shaft lumen 221 xis in communication with the second inner catheter lumen 201 x.Moreover, the proximal portion of the shaft 220 x is fixed to thecylindrical portion 97 x of the inner catheter hub 210 x as shown inFIG. 28 such that the shaft lumen 221 x is in communication with thesecond inner catheter hub lumen 212 x. The second inner catheter hublumen 212 x, the shaft lumen 221 x, and the second inner catheter lumen201 x function as a flow path through which a liquid such as a contrastagent, physiological saline, or a drug flows.

Next, the action of a catheter assembly 180 x according to the eighthmodified example is described.

In the catheter assembly 180 x according to the eighth modified example,the second inner catheter lumen 201 x is formed in the tubular body 200x of the inner catheter 190 x as shown in FIGS. 26 and 27. Moreover, asshown in FIG. 28, the shaft lumen 221 x is formed in the shaft 220 x,and the second inner catheter hub lumen 212 x is formed in the innercatheter hub 210 x. The second inner catheter lumen 201 x, the shaftlumen 221 x, and the second inner catheter hub lumen 212 x are incommunication with one another. Accordingly, in a state where a guidewire is inserted into the inner catheter lumen 83 x and the innercatheter hub lumen 94 x, when a syringe accommodating a liquid such as acontrast agent, physiological saline, or a drug is connected to the port211 x, and the liquid is injected, the liquid is discharged to thedistal side of the catheter assembly 180 x through the second innercatheter hub lumen 212 x, the shaft lumen 221 x, and the second innercatheter lumen 201 x. At this time, the liquid does not flow inside theouter catheter lumen 41 x into which the guide wire is inserted.Accordingly, the liquid can be effectively discharged to the distal sideof the catheter assembly 180 x without being interrupted by the guidewire.

The aforementioned catheter assembly used in the treatment method of thethird embodiment is not limited to the above catheter assembly, and canbe modified in various ways by those skilled in the art within thetechnical idea disclosed here. For example, as a ninth modified exampleshown in FIG. 29, an outer catheter body 230 x may be provided with areinforcing member in which a helical slit 231 x is formed between aninner layer and an outer layer. Moreover, in the proximal portion of theouter catheter body 230 x, a slit 231 x is formed at a certain pitch soas to form a rigidity uniform portion 232 x (a portion of uniformrigidity throughout). In addition, the distal portion of the outercatheter body 230 x includes a rigidity transition portion 233 x inwhich the pitch of the slit 231 x is gradually reduced toward the distalend. In the rigidity uniform portion 232 x formed as above, the rigidityis uniform in the axis direction, and in the rigidity transition portion233 x, the rigidity is reduced toward the distal end. Furthermore, theproximal end (proximal-most end) of the tubular body 80 x is on theproximal side of the distal end (distal-most end) of the rigidityuniform portion 232 x. If the above construction or configuration isadopted, the proximal end of the tubular body 80 x is not positioned inthe middle of the rigidity transition portion 233 x, and transition ofrigidity of the outer catheter body 230 x can be excellently maintained.Accordingly, when inserting the catheter assembly into the body lumen,the surgeon can more safely insert the catheter assembly into the bodylumen, while sufficiently securing pushability or sufficientlytransmitting torque to the distal side.

In addition, at least one of the outer catheter body and the innercatheter body may form a curve.

The use of the catheter assembly disclosed here by way of variousexamples is not particularly limited as long as it is used by beinginserted into the body lumen. Accordingly, the catheter assembly may be,for example, a catheter introducer in which the outer catheter functionsas a sheath and the inner catheter (shaft) functions as a dilator. Thebody lumen is not limited to a blood vessel and may be, for example, avessel, the ureter, the bile duct, the fallopian tube, the hepatic duct,and the like. Particularly, in recent years, it has been increasinglynecessary for the surgeon to deliver the catheter assembly to a bloodvessel of a lower limb through the radial artery or the subclavianartery by using the TRI technique. When the blood vessel of a lower limbis taken as a treatment site, for example, the iliac artery or thefemoral artery becomes the blood vessel as a treatment target. In thiscase, a distance between the site where the catheter assembly isinserted into the blood vessel and the treatment site inside the bloodvessel is rather long, and accordingly, the surgeon needs to use a longguide wire, inner catheter, and outer catheter. Therefore, when theblood vessel of a lower limb is treated by the TRI technique, thecatheter assembly according to the disclosure here that inhibits theguide wire from being excessively lengthened is suitable.

The number of catheters constituting the catheter assembly is notparticularly limited as long as the assembly is constituted of two ormore catheters. Therefore, for example, the catheter assembly mayinclude another catheter outside the outer catheter, or may includeanother catheter between the outer catheter and the inner catheter.

The detailed description above describes embodiments of a catheterassembly and method representing examples of the catheter assembly andmethod disclosed here. The invention is not limited, however, to theprecise embodiments and variations described. Various changes,modifications and equivalents can effected by one skilled in the artwithout departing from the spirit and scope of the invention as definedin the accompanying claims. It is expressly intended that all suchchanges, modifications and equivalents which fall within the scope ofthe claims are embraced by the claims.

What is claimed is:
 1. A treatment method for treating a treatmenttarget of at least one lower limb of a patient's body, the patient'sbody including an aorta, the method comprising: introducing a catheterassembly into a blood vessel of an arm of the patient's body, thecatheter assembly possessing a distal end and comprising a firstcatheter possessing a lumen and a second catheter possessing a lumen,the second catheter being positioned in the lumen of the first catheter,the first and second catheters each possessing a distal end; theintroducing of the catheter assembly into the blood vessel includingmaintaining a portion of the catheter assembly exposed outside the body;delivering the catheter assembly to a predetermined position of onelower limb of the at least one lower limb so that the distal ends ofboth the first and second catheters pass through the aorta by operatingthe portion of the catheter assembly that is exposed outside the body;after delivering the catheter assembly to the predetermined position ofthe one lower limb, advancing a treatment device through the firstcatheter and toward the treatment target; and treating the treatmenttarget using the treatment device.
 2. The treatment method according toclaim 1, further comprising, before the advancing of the treatmentdevice through the first catheter and toward the treatment target:advancing the distal end of the second catheter, or a distal end of athird catheter introduced after withdrawal of the second catheter fromthe first catheter, near the treatment target through the firstcatheter; and the advancing of the treatment device through the firstcatheter and toward the treatment target comprising advancing thetreatment device through the lumen of the second catheter or through alumen in the third catheter.
 3. The treatment method according to claim1, wherein the one lower limb is a first lower limb, the treatmentmethod further comprising, after the treating of the treatment target:retreating the distal end of the first catheter to a connection positionat which a blood vessel of the first lower limb and a blood vessel of asecond lower limb are connected to each other; delivering the firstcatheter to a predetermined position of the second lower limb from theconnection position after the retreating of the distal end of the firstcatheter to the connection position; and advancing an individual sitetreatment device to a treatment target of the second lower limb bymoving the individual site treatment device through the first catheterafter delivering the first catheter to the predetermined position of thesecond lower limb; and treating the treatment target of the second lowerlimb by operation of the individual site treatment device.
 4. Thetreatment method according to claim 3, further comprising, beforetreating the treatment target of the second lower limb by operation ofthe individual site treatment device: advancing to an individual site,in the second lower limb near the treatment target of the second lowerlimb, the distal end of the second catheter or a distal end of a thirdcatheter, which is introduced into the first catheter after withdrawingthe second catheter from the first catheter, through the first catheter;and wherein the advancing of the individual site treatment device to thetreatment target of the second lower limb comprises advancing theindividual site treatment device through the lumen of the secondcatheter or the third catheter.
 5. The treatment method according toclaim 1, further comprising introducing a sheath having an outerdiameter equal to or smaller than 2.8 mm into the blood vessel of thearm of the patient's body, the introducing of the catheter assembly intothe blood vessel of the arm of the patient's body comprising introducingthe catheter assembly into a lumen of the sheath.
 6. The treatmentmethod according to claim 1, wherein the treatment target is located ina blood vessel closer to a peripheral side than to a popliteal artery inthe one lower limb, and the delivering of the catheter assembly to thepredetermined position of the one lower limb includes delivering thedistal end of the catheter assembly to a femoral artery or an iliacartery, and during the advancing of the treatment device, the treatmentdevice is sent to the femoral artery from the catheter assembly, and thetreatment device is advanced to the popliteal artery.
 7. The treatmentmethod according to claim 1, wherein the treatment target is located ina blood vessel closer to a peripheral side than to a popliteal artery inthe one lower limb, and the delivering of the catheter assembly to thepredetermined position of the one lower limb includes positioning thedistal end of the catheter assembly in the popliteal artery or in theblood vessel at the peripheral side.
 8. The treatment method accordingto claim 1, wherein the treatment target is present near a knee, near acalf, or near an ankle of the patient.
 9. A treatment method fortreating a treatment target of at least one lower limb in a body of apatient, the patient's body including an aorta, the method comprising:inserting a guide wire into a catheter assembly, the catheter assemblycomprising an inner catheter and an outer catheter each possessing alumen and a distal end, the inner catheter being disposed in the lumenof the outer catheter with the distal end of the inner catheterprotruding distally beyond the distal end of the outer catheter, theinserting of the guide wire including inserting the guide wire into thelumen of the inner catheter while the inner catheter is disposed in thelumen of the outer catheter; introducing the guide wire into a bloodvessel of an arm of the patient's body, and introducing the catheterassembly into the blood vessel of the arm by guiding the catheterassembly along the guide wire; delivering a distal ends of the inner andouter catheters through the aorta and to a predetermined position of onelower limb of the at least one lower limb by operating a portion of thecatheter assembly that is exposed outside the patient's body;withdrawing the inner catheter from the lumen of the outer catheterwhile the outer catheter and the guide wire remain inside the bloodvessel after delivering the distal ends of the inner and outer cathetersthrough the aorta and to the predetermined position of the one lowerlimb; introducing a treatment device for treating the treatment targetinto the blood vessel and along the guide wire after the withdrawing ofthe inner catheter, and advancing the treatment device to the treatmenttarget through the outer catheter; and treating the treatment targetusing the treatment device.
 10. The treatment method according to claim9, wherein the outer catheter includes a tubular outer catheter body andan outer catheter hub disposed at a proximal end of the outer catheterbody, the lumen of the outer catheter passing through both the outercatheter body and the outer catheter hub; wherein the inner catheterincludes an inner catheter body positioned in the lumen in the outercatheter body, and an inner catheter hub positioned in a proximal end ofthe inner catheter body and connected to the outer catheter hub; andfurther comprising, before the inserting of the guide wire into thecatheter assembly, disposing the inner catheter body in the lumen in theouter catheter body, and connecting the inner catheter hub to the outercatheter hub.
 11. The treatment method according to claim 10, whereinthe inner catheter body includes a shaft and a tubular body, the shaftpossessing a distal end connected to the tubular body, the lumen of theinner catheter including a first inner catheter lumen passing throughthe tubular body, the tubular body and the outer catheter body bothpossessing respective distal-most ends; and during the inserting of theguide wire into the catheter assembly, the distal-most end of thetubular body is positioned distally of the distal-most end of the outercatheter body, and a proximal-most end of the tubular body is positionedin the lumen of the outer catheter.
 12. The treatment method accordingto claim 11, wherein the tubular body includes a second inner catheterlumen that opens at opposite ends in a distal portion and a proximalportion of the tubular body; and further comprising, during thedelivering of the distal ends of the inner and outer catheters throughthe aorta and to the predetermined position of the one lower limb,injecting a fluid through the inner catheter hub of the catheterassembly such that the fluid is injected into the blood vessel throughthe second inner catheter lumen.
 13. A treatment method for treating atreatment target in a lower limb of a patient's body, the patient's bodyincluding an aorta, the method comprising: introducing a catheterassembly into a blood vessel of an arm of the patient's body, thecatheter assembly comprising a first catheter possessing a lumenextending throughout a length of the first catheter and a secondcatheter possessing a lumen extending throughout a length of the secondcatheter, the second catheter being positioned in the lumen of the firstcatheter, the first and second catheters each possessing a distal end;the introducing of the catheter assembly into the blood vessel includingmaintaining a portion of the catheter assembly exposed outside the body;advancing a distal end portion of the catheter assembly into the lowerlimb of the patient's body by way of the aorta while the second catheterremains positioned in the lumen of the first catheter by operating theportion of the catheter assembly that is exposed outside the body sothat the distal ends of both the first and second catheters arepositioned in the lower limb of the patient's body; introducing atreatment device into the lumen of the first catheter while the distalend of the first catheter is positioned in the lower limb of thepatient's body; advancing the treatment device through the lumen of thefirst catheter while the distal end of the first catheter is positionedin the lower limb of the patient's body to move the treatment devicetoward the treatment target in the lower limb of the patient's body; andtreating the treatment target using the treatment device.
 14. Thetreatment method according to claim 13, wherein the introducing of thetreatment device into the lumen of the first catheter comprisesintroducing the treatment device into the lumen of the second catheter,and wherein the advancing of the treatment device through the lumen ofthe first catheter comprises advancing the treatment device through thelumen of the second catheter.
 15. The treatment method according toclaim 13, further comprising completely removing the second catheterfrom the lumen of the first catheter after the distal ends of both thefirst and second catheters are positioned in the lower limb of thepatient's body and before the introducing of the treatment device intothe lumen of the first catheter.
 16. The treatment method according toclaim 13, further comprising introducing a sheath into the blood vesselof the arm of the patient's body before introducing the catheterassembly into the blood vessel of the arm of the patient's body, theintroducing of the catheter assembly into the blood vessel of the arm ofthe patient's body comprising introducing the catheter assembly into alumen in the sheath.
 17. The treatment method according to claim 16,wherein the introducing of the sheath into the blood vessel of the armof the patient's body comprises introducing a sheath having an outerdiameter equal to or smaller than 2.8 mm into the blood vessel of thearm of the patient's body.
 18. The treatment method according to claim13, wherein the treatment target is located in a blood vessel closer tothe peripheral side than to the popliteal artery in the lower limb, andthe delivery of the distal end of the catheter assembly to thepredetermined position of the lower limb includes delivering the distalend of the catheter assembly to a femoral artery or iliac artery, andduring the advancing of the treatment device, the treatment device issent to the femoral artery from the catheter assembly, and the treatmentdevice is advanced to the popliteal artery.
 19. The treatment methodaccording to claim 13, wherein the first catheter includes a proximalend at which is located a first catheter hub, and the second catheterincludes a proximal end at which is located a second catheter hub, theintroducing of the catheter assembly into the blood vessel comprisingintroducing the catheter assembly into the blood vessel while the firstcatheter hub is fixed to the second catheter hub so that the first andsecond catheters as well as the first and second catheter hubs movetogether as a unit.